Water Quality Control and
Dr. Khamis AL-Mahallawi
• Water is a chemical substance with the chemical formula
• Its molecule contains one oxygen and two hydrogen atoms
connected by covalent bonds.
• Water is a liquid at ambient conditions, but it often co-exists
on Earth with its solid state, ice, and gaseous state (
water vapor or steam). Water also exists in a liquid crystal
state near hydrophilic surfaces
Chemical and physical properties of water
• Water is a liquid at standard temperature and pressure. It is tasteless
• water is a polar molecule
• Water is a good solvent (universal solvent).
• Substances that dissolve in water are known as hydrophilic (waterloving) substances, while those that do not mix well with water are
known as hydrophobic (water-fearing) substances.
• All the major components in cells (proteins, DNA and
polysaccharides) are dissolved in water.
• Pure water has a low electrical conductivity,
• The boiling point of water is dependent on the barometric pressure.
(on the top of Mt. Everest water boils at 68 °C, compared to 100 °C
at sea level.
Chemical and physical properties of water
water is moderate Earth's climate by buffering large
fluctuations in temperature.
Water is miscible with many liquids, such as ethanol,
forming a single homogeneous liquid.
water and most oils are immiscible usually forming layers .
As a gas, water vapor is completely miscible with air.
Water can be split by electrolysis into hydrogen and oxygen.
The energy required to split water into hydrogen and oxygen
by electrolysis or any other means is greater than the energy
that can be collected when the hydrogen and oxygen
Elements which are electroposistive than hydrogen such as
lithium, sodium, calcium, and potassium displace hydrogen
from water, forming hydroxides.
development that meets the needs of the
present without compromising the ability of
future generations to meet their own needs.
Sustainable development / water
In relation to water the concepts set out above can be
interpreted as follows.
• Water is a scarce resource which should be viewed as both
a social and an economic resource.
• Water should be managed by those who most use it, and all
those who have an interest in its allocation should be
involved in the decision making.
• Water should be managed within a comprehensive
framework, taking into account its impact on all aspects of
social and economic development.
Units of Concentration
• Solution: a mixture consisting of a solute and a
• Solute: component of a solution present in the
• Solvent: component of a solution present in the
• Concentration: amount of a solute present in a
solution per amount of solvent
)%(Concentration / Percent Composition by Mass
Concentration may be expressed several different ways
• Percent Composition by Mass )%(
Where the mass of the solution is equal to the mass of the solute plus
the mass of the solvent.
Example: Determine the percent composition by mass of a 100 g salt
solution which contains 20 g of NaCl salt.
Solution: 20 g NaCl / 100 g solution x 100 = 20% NaCl solution.
(Concentration / Volume Percent )% v/v
• Volume Percent (% v/v): most often is used when preparing
solutions of liquids. Volume percent is defined as:
• Note that volume percent is relative to volume of solution, not
volume of solvent.
• For example, wine is about 12% v/v ethanol. This means there are
12 ml ethanol for every 100 ml of wine.
• It is important to realize liquid and gas volumes are not necessarily
additive. If you mix 12 ml of ethanol and 100 ml of wine, you will
get less than 112 ml of solution.
Concentration / Mole Fraction
Mole Fraction )X(: This is the number of moles of a compound divided by the total
number of moles of all chemical species in the solution.
What are the mole fractions of the components of the solution formed when 92 g
glycerol is mixed with 90 g water? (molecular weight water = 18; molecular weight
of glycerol = 92)
90 g water = 90 g x 1 mol / 18 g = 5 mol water
92 g glycerol = 92 g x 1 mol / 92 g = 1 mol glycerol
total mol = 5 + 1 = 6 mol
xwater = 5 mol / 6 mol = 0.833
x glycerol = 1 mol / 6 mol = 0.167
It's a good idea to check your math by making sure the mole fractions add up to 1:
xwater + xglycerol = .833 + 0.167 = 1.000
Concentration / Molarity
Molarity )M(: is probably the most commonly used unit of concentration. It is
the number of moles of solute per liter of solution (not necessarily the same as
the volume of solvent).
Example: What is the molarity of a solution made when water is added to 11 g
CaCl2 to make 100 mL of solution?
11 g CaCl2 / (110 g CaCl2 / mol CaCl2) = 0.10 mol CaCl2
100 mL x 1 L / 1000 mL = 0.10 L
molarity = 0.10 mol / 0.10 L
molarity = 1.0 M
Concentration / Molarity
How many millilieters of 5.5 M NaOH are needed to prepare
300 mL of 1.2 M NaOH?
5.5 M x V1 = 1.2 M x 0.3 L
V1 = 1.2 M x 0.3 L / 5.5 M
V1 = 0.065 L
V1 = 65 mL
• So, to prepare the 1.2 M NaOH solution, you pour 65 mL
of 5.5 M NaOH into your container and add water to get
300 mL final volume
Concentration / Normality
Normality (N): is equal to the gram equivalent weight of a
solute per liter of solution. A gram equivalent weight or
equivalent is a measure of the reactive capacity of a given
molecule. Normality is the only concentration unit that is
Example: 1 M sulfuric acid (H2SO4) is 2 N for acid-base
reactions because each mole of sulfuric acid provides 2
moles of H+ ions. On the other hand, 1 M sulfuric acid is 1 N
for sulfate precipitation, since 1 mole of sulfuric acid
provides 1 mole of sulfate ions.
Concentration / Mass per unit volume
Mass per unit volume it can be given in mg/m3 - mg/l (mg/mL) (mg/cm3)
Note that 1 mL = 1 cm3 and that cm3 is sometimes denoted as a "cc".
In air pollution measurements, the mass of pollutant is expressed as
micrograms of pollutant per cubic meter of air (1 millionth of a grams per
cubic meter of air), μg/m3 - mass of species per unit volume of air.
In water, mass/volume concentration of mg/l and μg/m3 are common.
In most aqueous systems, ppm is equivalent to mg/l.
Concentration units in water chemistry
The concentration of a chemical in a water sample is commonly measured
and reported in ;
• mass concentration, often expressed in units of g/L - mg/L
• parts per million on a weight : weight basis (1 mg/L = 1 ppm)
• equivalent weight ; Example of calculation:
Na+ atomic weight 23
1 meq/l = 23/1 mg/l
Ca2+atomic weight 40
1 meq/l = 40/2 mg/l
• For neutrality and to calculate the balance error of water sample
test, the total amount of cations expressed in meq/l must be equal
to the total amount of anions expressed in meq/l.
Objective in water quality control
Water quality is the physical, chemical and biological characteristics of water.
A major objective in water quality control work is to reduce the incidence of waterrelated diseases
i.e water free from
visible suspended matter
excessive color, taste and odor
objectionable dissolved matter
bacteria indicative of faecal pollution.
The concept of integrated pollution control (IPC) is highly relevant to the effective
conservation and management of the global environment
GENERAL CLASSIFICATION OF POLLUTANTS
• Pollution: is defined as the deterioration of the
• Pollution is the introduction of contaminants into a
natural environment that causes instability, disorder,
harm or discomfort to the ecosystem i.e. physical
systems or living organisms.
• Pollution is often classed as point source or
nonpoint source pollution.
SOURCES OF WATER POLLUTION
When pollution control is considered, these
questions should be asked and answered.
1. Can the pollution source be eliminated?
2. Can the pollution source be minimized?
3. Can the pollutants be reused?
4. Can the pollutant be treated?
Common sources of pollution
INDUSTRIAL SOURCES OF WATER POLLUTION
MUNICIPAL SOURCES OF WATER POLLUTION
AGRICULTURAL SOURCES OF WATER POLLUTION
NATURAL SOURCES OF WATER POLLUTION
STORMWATER SOURCES OF WATER POLLUTION
LANDFILL WATER POLLUTION SOURCES
LEAKING UNDERGROUND STORAGE TANK WATER
INDUSTRIAL SOURCES OF WATER
1. Non-Contact Water
• Boiler feed water
• Cooling water
• Heating water
• Cooling condensate
2. Contact Water
• Water used to transport products, materials or chemicals
• Washing and rinsing water (product, equipment, floors)
• Solubilizing water
• Diluting water
• Direct contact cooling or heating water
• Shower and sink water
MUNICIPAL SOURCES OF WATER POLLUTION
The non-industrial municipal sources of water are typically
• Commercial establishments
• Institutions (schools, hospitals, prisons, etc)
• Governmental operations
It is assumed that a non-industrial municipal wastewater
source will contain no pollutants except for the following:
• Food waste
• Laundry wastewater
• Sink, shower, and bath water
AGRICULTURAL SOURCES OF WATER POLLUTION
• Agricultural water pollutants are transported to an aboveground or
underground receiving stream by periodic stormwater
• Agricultural wastewater can be of animal or vegetable origin or be from a
nutrient, fertilizer, pesticide or herbicide source.
• Animal or vegetable sources will be limited to biodegradable feces, urine or
• Nutrients or fertilizers will be typically some formulation of carbon,
phosphorous, nitrogen and/or trace metals.
• Pesticides and herbicides will consist of formulated organic chemicals, many
with complex molecular structures, designed to be very persistent in the
environment. Pesticides such as Chlorodane and Heptachlor, which consist of a
multitude of different organic chemicals, can still exist in the soil around
World War II barracks.
NATURAL SOURCES OF WATER POLLUTION
• Areas unaffected by human activity can still pollute
receiving steams due to stormwater runoff, which can
be classified into animal, vegetable and soil sources.
• Again, animal and vegetable water pollution sources
should be readily biodegradable.
• Soil sources will consist of any organic and inorganic
material in the soil.
STORMWATER SOURCES OF WATER
• Stormwater has been mentioned above under
agricultural and natural sources of water
pollution, but will also transport industrial and
municipal water pollutants to a receiving
stream or underground water supply.
Industrial Stormwater Sources
Any solid or liquid material or chemical stored, leaked or spilled on the
ground from an industrial operation can be transported by stormwater to
a recovery stream and become a pollutant.
These sources can be from any or all of the following:
• Outside process areas
• Inside process areas which discharge to the outside
• Roof drains
• Parking lots
• Loading/unloading areas
• Storage areas
• Wastewater treatment areas
• Soil runoff
• Tank farms
Municipal Stormwater Sources
Any material or chemical deposited on the ground in a
municipality can likewise be transported to a receiving
stream as a pollutant.
• Petroleum product spills and leaks
• Garbage and trash
• Soil runoff
• Surfacing underground sewage disposal systems
• Spills and leaks from material or chemical transport
LANDFILL WATER POLLUTION SOURCES
• Public, private, and industrial landfills can be a source of stormwater
pollution because of runoff from the surface and underground leachate.
• When stormwater leaches through the surface cap and downward
through the landfill, the horizontally or vertically migrating discharge
from below the landfill is known as leachate and can pollute surface or
• Because of the bacteria present in the dirt and in landfill material, there
will always be aerobic and anaerobic biological activity occurring in a
physical pollutants are categorized as follows:
1. Solids content
2. Solids type
PHYSICAL POLLUTANTS/ Solids Content
For regulatory and treatment purposes, total solids (TS) can first be
classified as suspended or dissolved.
Total Solids: is the material residue left in a vessel after evaporation
of a sample and its subsequent drying in an oven at 103 to 105°C for
Total Suspended Solids (TSS) : is that portion of the Total Solids
that are retained on a no-ash glass fiber filter disc of approximately
0.45 mm pore size.
Relationship Between TS, TSS and TDS. These three solids tests
can be related with :
TS = TSS +TDS
PHYSICAL POLLUTANTS / Solid Type
The most basic solids differentiation is between settleable and floatable solids
Settleable Solids. A liter of wastewater is settled in an Imhoff cone for one
hour and the milliliters of solids accumulating in the bottom is reported as
settleable solids (S/S) in ml/l
Flotable Solids. The quickest and simplest test for floatable solids is to test
TSS as explained above in a well mixed sample of the wastewater and then
let the wastewater float quiescently for one hour. Then take a sample of the
wastewater with a pipette from under the float and above any sediment. Run
a TSS test on the second pipette sample and report as non-flotable,
suspended solids (NFSS).
The relation with TSS will be as follows:
TSS = FSS + NFSS
where FSS = Flotable Suspended Solids.
Total suspended solids
PHYSICAL POLLUTANTS / Solid Type
• Total Volatile Solids. The total volatile solids (TVS) test is used to determine
whether a solid is organic, as approximated by being volatile, or inorganic
• To determine total volatile solids (TVS), the residue from the TS test described
above is ignited in a weighed dish in a furnace at 550°C ± 50°C for 15 to 20
minutes and then weighed. The loss of weight is reported as TVS. The
remaining weight is total non-volatile solids (TNVS).
• The relationship between Total Solids and Volatile Solids is
TS = TVS +TNVS
• The total volatile solids test indicates the amount of the total solids which can
potentially be destroyed chemically or biologically, volatilized through
stripping, or adsorbed.
• The non-volatile solids are typically inorganic and cannot be destroyed. These
solids must be converted or removed by some physical or chemical method
PHYSICAL POLLUTANTS / Solid Type
• Total Volatile Suspended Solids. The suspended solids collected
on the no-ash filter in the TSS test described above can be ignited
in a furnace at 550°C ± 50°C for 15 to 20 minutes to determine
the total volatile suspended solids (TVSS).
• The TVSS will be the loss of weight and the total nonvolatile
suspended solids (TNVSS) will equal the remaining weight.
• The relationship between Total Suspended Solids and Volatile
Suspended Solids can be expressed as:
TSS = TVSS +TNVSS
PHYSICAL POLLUTANTS / Solid Type
• Total Volatile Dissolved Solids. If the dried filtrate from the
TDS test is ignited in a furnace at 550°C + 50°C for 15 to 20
minutes, the residue can be reported as total non-volatile
dissolved solids (TNVDS) and the loss of weight as total
volatile dissolved solids (TVDS).
TDS = TVDS + TNVDS
PHYSICAL POLLUTANTS / Turbidity
• Turbidity in water can be caused by suspended matter such as silt,
clay, organic matter, organic compounds, or dissolved inorganics.
• Turbidity is determined by the optical property that causes light to
be scattered, adsorbed or reflected rather than transmitted in a
straight line through or into a liquid.
• In the nephelometric method, the intensity of scattered light in a
sample is compared with the intensity of light scattered by a
standard reference solution under the same conditions.
• The higher the intensity of scattered light, the higher the turbidity.
PHYSICAL POLLUTANTS/ Color
• Color. water is “colored” if it is not completely clear. Color can be
suspended color (apparent color) or dissolved color (true color)
• Suspended particles can be removed by settling or filtration, and
can be considered as suspended solids regardless of whether they
• Dissolved color is of more concern and may be caused by
vegetable or mineral dyes, other inorganic industrial wastes, or by
organic material from stormwater runoff.
• Dissolved color should be considered as inorganic or organic
chemical water quality
• Color is quantitatively determined by visual comparison with a
PHYSICAL POLLUTANTS / Odor
Odor is rare as a permit pollutant, but may be prohibited in a pretreatment system.
The accepted odor test is the Threshold Odor Test in which a sample is diluted
with pure water until the least perceptible odor is noticed.
The Minimum Detectable Threshold Odor Concentration (MDTOC) is reported as
units or dilutions required to reduce an odor to its detectable limit.
If several people independently perform the Threshold Odor Test, the averaged
Threshold Odor Number (TON) can be relatively accurate
the MDTOC equals the initial sample volume divided by the barely ((بالكاد
detectable sample volume:
MDTOC = 100 ml / 25 ml = 4
PHYSICAL POLLUTANTS / Taste - Temperature
Taste. There are only four true tastes that can be recognized by tongue and
palate sensory nerves: Bitter – Salty – Sour - Sweet
There are three methods of determination:
The Flavor Threshold Test is similar to the odor test and is the greatest dilution
of a sample using pure water which yields a perceptible taste.
The Flavor Rating Assessment is a scale for rating a drinking water as
acceptable or not.
The Flavor Profile Analysis is a comparison between a wastewater taste and that
of a documented sensory quality judged acceptable by trained testers.
Temperature. The temperature of a water is a physical water quality parameter
since temperature can have a negative effect on aquatic life, especially the
propagation of fish. Various types of fish require certain temperatures for
existence and a lower temperature for propagation.
• Electrical conductivity (EC) is a measure of the ability of water to conduct an
The conductivity of a solution depends on:
• Concentration of the ions (higher concentration, higher EC)
• Temperature of the solution (high temperature, higher EC)
• Specific nature of the ions (higher specific ability and higher valence, higher
• Knowing the appropriate value of K for a particular water, the measurement of
conductivity provides a rapid indication of TDS content.
• the electrical conductivity is expressed in Siemens per meter or milli Siemens
per meter at 25ºC (mS.m-1).
Radioactivity. Measurements of gross beta and gama activity are routine
Radioactive substances are those that are unstable in nature.
Radioactive substances in ground water, such as radium, uranium and
thorium, occur naturally
Naturally occurring radon (an alfa emitter) can be a possible long-term
health hazard with some groundwater.
The acidity of the water, which may be increased by the presence of
elevated levels of nitrates associated with agricultural land use, is believed
to increase the amount of radium that dissolves into groundwater from
contact with sands and soils.
Unit of concentration is picocurie per liter
three primary types of radiation:
Alpha - these are fast moving
Beta - these are fast moving
electrons. Since electrons are might
lighter than helium atoms, they are
able to penetrate further, through
several feet of air, or several
millimeters of plastic or less of
very light metals.
Gamma - these are photons, just
like light, except of much higher
energy, typically from several keV
to several MeV.
How can beta particles affect people's health?
Beta radiation can cause both acute and chronic health effects. Acute exposures
are uncommon. Contact with a strong beta source from an abandoned industrial
instrument is the type of circumstance in which acute exposure could occur.
Chronic effects are much more common.
Chronic effects result from fairly low-level exposures over a along period of
time. They develop relatively slowly (5 to 30 years for example). The main
chronic health effect from radiation is cancer. When taken internally beta
emitters can cause tissue damage and increase the risk of cancer. The risk of
cancer increases with increasing dose.
Some beta-emitters, such as carbon-14, distribute widely throughout the body.
Others accumulate in specific organs and cause chronic exposures:
Iodine-131 concentrates heavily in the thyroid gland. It increases the risk of
thyroid cancer and other disorders.
Strontium-90 accumulates in bone and teeth.
• Chemical pollutants can be organic or inorganic.
• There are thousands of organic pollutants consisting of various
combinations of carbon, hydrogen, and perhaps oxygen and/or
many other inorganic or organic molecules.
• In general, organic pollutants are more biodegradable with fewer
carbon and/or other molecules attached
• Inorganic chemical pollutants can be categorized into pure
chemical pollutants and chemical indicators,
Naturally occurring chemicals
• WHO has established guideline values for 9 compounds that can
occur naturally in water.
• Arsenic, As
• Arsenic in drinking water is a global threat to health, potentially
affecting about 140 million people in at least 70 countries
• Arsenic can occur in drinking water either as the reduced species
AsIII (arsenite) or the oxidized form, AsV (arsenate).
• Arsenic occurs naturally in soils/rocks, with concentrations of
about 2-10 mg/kg.
• Arsenic causes skin lesions, but other effects can include
weakness, diarrhoea, vascular disease and diabetes mellitus. The
main health concerns are cancers of the skin or internal organs
Naturally occurring chemicals
Barium, Ba. GV 0.7 mg/L (chronic exposure can cause hypertension in
humans, leading to the GV of 0.7 mg/L. Short-term exposure to high levels of
barium can cause gastrointestinal disturbances and muscular weakness )
Chromium, Cr. GV 0.05 mg/L (can cause lung cancer in humans)
Boron, B. GV 0.5 mg/L (ingestion can cause lower foetal weight and testicular
Fluorine, F. GV 1.5 mg/L (dental fluorosis -skeletal fluorosis involving
stiffness and pain in joints)
Manganese, Mn. GV 0.4 mg/L (strong unpleasant metallic taste - give rise to
the deposition of black deposits in pipes)
Molybdenum GV 0.07 mg/L (diarrhea, greying of hair and lowered growth
Selenium, Se. GV 0.01 mg/L (liver and kidney damage and hair and fingernail
Uranium U GV 0.015 mg/L (kidney damage)
Chemicals from industrial sources and
Cadmium, Cd. GV 0.003 mg/L: Cadmium is used in metal plating, plastics,
pigments and batteries (is cumulative in the kidney and liver organs and can
Cyanide GV 0.07 mg/L : used in metal finishing and the production of
plastics such as nylon. (Cyanide is acutely toxic, primarily affecting the
thyroid and the nervous system)
Mercury Hg GV 0.006 mg/L: Mercury is used in the electrolytic production
of chlorine; in electrical appliances such as dry-cell batteries, fluorescent light
bulbs and switches; and in thermometers.
kidneys, brain, and nervous system)
(cause serious damage to the
Chemicals from agricultural activities
Nitrate and nitrite NO3 - and NO2 - 50 and 3 mg/L
• (methaemoglobinaemia, or “bluebaby syndrome”)
• There is some evidence that nitrite can react with amines or amides in the body
to form nitrosamine, a known carcinogen
• WHO recommends a GV of 0.2 mg/L nitrite for long-term exposure
Ammonia, NH3, NH4
• Ammonia is present in nature as part of the Nitrogen Cycle.
• Ammonia, at certain concentrations, is toxic to fish and is therefore considered a
pollutant to waters classified for fish and wildlife.
• Ammonia is primarily in the NH3 or gaseous form below pH 7.0 and primarily in
the NH4+ or ammonium salt form above a pH of 7
Ammonium Oxidation HN4+ + 1/2O2 = NO2- + HOH + 2H+
Nitrite Oxidation NO2- + 1/2O2 = NO3•
Denitrification: NO3- -----> NO -----> N2O -----> N2 gas
• Over 600 organic compounds have been detected
in raw water sources and most of them are due to
human activity or industrial operations.
• Substances include benzene, chlorophenols,
pesticides, polynuclear aromatic hydrocarbons
(PAH) and trihalomethanes (THM).
• present in very low concentrations, but there is
some concern about possible health effects
Pesticides may enter surface water or groundwater primarily as runoff
following application to crops, though inappropriate disposal or accidental
The potential of a pesticide to contaminate drinking water is affected by its
solubility and biodegradability; the method of application; and environmental
factors such as soil, weather, season and proximity to water resources.
Early pesticides were compounds of toxic metals such as arsenic, mercury,
copper or lead
The first organic pesticides were chlorinated hydrocarbons such as DDT,
aldrin, dieldrin, chlordane, endrin, heptachlor, lindane and pentachlorophenol.
they are resistant to biodegradation and can accumulate in food supplies
most commonly used pesticides today include organophosphorus compounds
and carbamates, both of which are relatively soluble and biodegradable.
Chemicals from water treatment and distribution systems
– Free chlorine (target residual concentration in the range of 0.2 to 1 mg/L )
– Chloramines (a mixture of monochloramine, dichloramine and
trichloramine formed when ammonia is present in chlorinated water)
– Silver has a bacteriostatic effect and is sometimes used for emergency
disinfection (skin and hair become discoloured)
– chlorine dioxide, iodine, and ozone. WHO has not set guideline values for
these compounds either because they decay rapidly in water
Disinfectant by-products (DBPs) i.e trihalomethanes, brominated, haloacetic
acids, halogenated ketones and haloacetonitriles - WHO has set GVs for 14
Contaminants from treatment chemicals (Aluminum causes Alzheimer’s
disease , Iron)
Contaminants from pipes and fittings (organic compounds and heavy
metals i.e copper, lead)
Chemical Indicator Tests
developed to indicate water quality based on chemical characteristics which
can be simpler, less expensive, or more indicative of water quality than a
chemical compound test.
CaCO3 is used as a standard for many of the indicator tests since its molecular
weight is 100 and calculations are simplified
• pH is the negative logarithm of the hydrogen ion concentration in water.
• is used to indicate the intensity of the acidic or basic character of a solution.
• pH is normally determined electrometrically, but can be estimated using titration
or litmus paper.
• Water is only weakly ionized, as shown by the equilibrium
• H20 ~ H + + OH• 10-7 molar concentrations of H + and OH- are present at equilibrium
[H +] [OH-] = K = 1.01 X 10 -14 mole/L at 25
pH = -loglo [H +] = l o g lo 1/[H +]
• pH scale from 0 to 14 with 7 as neutrality, below 7 acid and above 7 alkaline
• Many chemical reactions are controlled by pH and biological activity is usually
restricted to a fairly narrow pH range of 5-8
• Highly acidic or highly alkaline waters are undesirable because of corrosion
problems and possible difficulties in treatment
The acidity of water is an indicator of its capacity to react with a strong base
to a designated pH.
Acidity or low pH of drinking water is usually a result of natural geological
conditions at the site, possibly compounded by acid rain
Water with a pH value less than 7 indicates acidity and tends to be corrosive
The concept of acidity is opposite that of alkalinity and is also based on the
The acidity of a water source is generally attributable to the carbonate molecules
H2CO3 and HCO3- and sometimes to strong acids, namely, H+.
H+ + OH- –-> H2O;
H2CO3 + OH- –-> HCO3-;
HCO3- + OH- –-> CO32-
When there are mostly acidic carbonate molecules in solution (H2CO3, HCO3-,
and H+), the pH is correspondingly acidic (< 7)
• if the carbonate molecules in solution are mostly HCO3-, CO32-, and OH-, the pH
is correspondingly basic (< 7).
Alkalinity is a function of the carbonate (CO32-), bicarbonate (HCO3-) and
hydroxide (OH) content of water.
• Titration with a standard acid to an end point of 8.3 PH is reported as
phenolphthaline alkalinity and titration to an end point of approximately 4.5 is
reported as total alkalinity.
• Most of the natural alkalinity in waters is due to HCO3- produced by the action
of groundwater on limestone or chalk
CaCO3 + H20 + CO2 ~ Ca(HCO3)2
Alkalinity is useful in waters in that it provides buffering to resist changes in
• It is normally divided into caustic alkalinity above pH 8.2 and total alkalinity
above pH 4.5.
• Alkalinity can exist down to pH 4.5 because of the fact that HCO 3- is not
completely neutralized until this pH is reached.
• The amount of alkalinity present is expressed in terms of CaCO 3.
Alk T = [HCO3-] + 2[CO32-] + [OH-] - [ H+ ]
Effects of pH on Various Buffers
Mixture of an acid (or base) and its conjugate base (or acid) chemical
CO2 + H2O ↔ H2CO3
H2CO3 ↔ HCO3- + H+
HCO3- ↔ CO32- + H+
CO2 + H2O ↔ H2CO3 ↔ HCO3- + H+ ↔ CO32- + 2 H+
Alkalinity and pH relationship
OH- is a strong base - HCO3- is a weak acid
more OH- than HCO3-, it completely neutralizes it and just have OHmore HCO3- than OH-, then it partially neutralizes it and detect only HCO 3Waters with low alkalinity are very susceptible to changes in pH.
Waters with high alkalinity are able to resist major shifts in pH.
As increasing amounts of acid are added to a water body, the pH of the water
decreases, and the buffering capacity of the water is consumed
Conductivity vs. Total dissolved solid
Conductivity is a quantification of the ability of water to carry an electric
• Dissolved solids" refer to any minerals, salts, metals, cations or anions
dissolved in water. This includes anything present in water other than the
pure water (H20) molecule and suspended solids.
Total hardness is the sum of calcium and magnesium concentrations
expressed in mg/l of CaCO3.
It is a measure of the capacity of water to precipitate soap.
Hardness is either calculated from the results of separate calcium and
magnesium tests or is determined from a color change when titrating a
sample with ethylenediaminetetracetic acid (EDTA).
Hardness may actually have a health benefit, but economic disadvantages of
a hard water include increased soap consumption and higher fuel costs.
Hardness is expressed in terms of CaCO3 and is divided into two forms,
– carbonate hardness: due to metals associated with HCO3– non-carbonate hardness: due to metals associated with SO42-, CI-, NO3-.
The non-carbonate hardness is obtained by substracting the alkalinity from
the total hardness.
If high concentrations of sodium and potassium salts are present, the
noncarbonated hardness value may be negative, since such salts could form
alkalinity without producing hardness.
The calcium and magnesium hardness is the concentration of calcium and
magnesium ions expressed as equivalent of calcium carbonate. The molar
mass of CaCO3, Ca2+ and Mg2+ are respectively 100,1 g/mol, 40,1 g/mol and
24,3 g/mol. The ratio of the molar masses are:
So total permanent water hardness expressed as equivalent of CaCO3 can be
calculated with the following formula:
The following values are used to give an indication about the water hardness:
Concentration as CaCO3
0 to 60 mg/L
60 to 120 mg/L
120 to 180 mg/L
Moderately hard water
Very hard water
Other Pollutants indicators
Hydrocarbons will be indicated as oil and grease. A mixture of all oils and
grease in trichlorofluoroethane can be added to silica gel to selectively remove
the fatty acids and leave only hydrocarbons for indication.
Oil and Grease. Most oil and grease tests quantify substances which are soluble
in trichlorotrifluoroethane. These tests will include the presence of certain
sulfur compounds, organic dyes and chlorophyll that are not volatilized.
Organic Pollutants. There are three tests commonly used to measure the total
organic pollutants present in a wastewater; biochemical oxygen demand
(BOD), chemical oxygen demand (COD), and total organic carbon (TOC).
(Dissolved oxygen (DO
• Oxygen is a most important element in water quality control.
• Oxygen is essential to maintain the higher forms of biological life and the
effect of a waste discharge on a river
• oxygen is only slightly soluble in water as indicated below for water with no
• Oxygen solubility is affected by the presence of chlorides which reduce the
saturation dissolved oxygen concentration
• Clean surface waters are normally saturated with DO, but such DO can be
removed rapidly by the oxygen demand of organic wastes.
• Game fish require at least 5 mg/l DO and coarse fish will not exist below about
2 mg/1 DO.
• Oxygen saturated waters have a pleasant taste and waters lacking DO have
• For boiler feed waters DO is undesirable because its presence increases the risk
Living organisms play major roles in many aspects of water quality control
the bacteriological analysis of drinking water supplies usually provides the
most sensitive quality assessment.
Raw sewage contains millions of bacteria per milliliter
Conventional treatment methods for sewage and organic wastewaters rely on
the ability of microorganisms to stabilize organic matter
Microorganisms can play valuable roles in wastewater treatment and
sometimes also in water treatment,
Biological pollutants have a combination of inorganic and organic constituents
and are characterized by being cellular in nature.
For biological treatment purposes, only the organic constituents can be
destroyed, and since all cellular material uses oxygen for energy, tests involve
the measurement of either carbon content or oxygen demand, or an actual
Organic compounds are generally unstable and may be oxidized biologically
or chemically to stable, relatively inert, end products such as CO2, NO3, H20.
An indication of the organic content of a waste can be obtained by measuring
the amount of oxygen required for its stabilization using
1. biochemical oxygen demand (BOD) - a measure of the oxygen required by
microorganisms whilst breaking down organic matter;
2. chemical oxygen demand (COD) - chemical oxidation using boiling
potassium dichromate and concentrated sulphuric acid.
)Biochemical Oxygen Demand (BOD
Biochemical oxygen demand or BOD is a chemical procedure for
determining the amount of dissolved oxygen needed by aerobic biological
organisms in a body of water to break down organic material present in a
given water sample at certain temperature over a specific time period.
It is most commonly expressed in milligrams of oxygen consumed per liter of
sample during 5 days of incubation at 20 °C.
The BOD indicates the total of carbonaceous and nitrogenous oxygen
Dissolved oxygen is measured initially after dilution and after incubation at
20°C for the time period of the test.
It is necessary to have a population of microorganisms present that is capable
of degrading the organic material in the sample.
Many unchlorinated domestic or industrial wastewaters will afford sufficient
bacteria for this purpose.
(The Chemical Oxygen Demand (COD
The Chemical Oxygen Demand (COD) test is a measure of the oxygen
required from a strong chemical oxidant for the destruction of an organic
The chemical oxidant selected for the COD test is potassium dichromate
The sample is oxidized by a boiling mixture of K2Cr2O7 and sulfuric acid using
an excess of K2Cr2O7.
After digestion, the remaining unreduced K2Cr2O7 is measured to determine the
amount consumed by titrating with ferrous ammonia sulfate (FAS) until the end
point is indicated by a sharp color change.
The COD takes about 2 to 3 hours to run compared to 5 days for a BOD test,
and can be run with a relatively simple and inexpensive kit.
Total Organic Carbon and Total Carbon
Total Organic Carbon (TOC) test is a more direct indication of organic
content than the BOD or COD test.
If a repeatable relationship between the three parameters is determined, TOC
can be used to estimate the other parameters.
The TOC test does not provide all of the information that the BOD and COD
The BOD test indicates the actual oxygen needed for biologically destroying the
The COD test indicates the chemical oxidation requirements for destruction,
the TOC test indicates the total organic matter present and is independent of the
oxidation state of the pollutant.
This test converts and removes inorganic carbon (CO + CO 2) and measures total
organic carbon by converting it into CO2 in a heated reaction chamber.
The CO2 is measured using infrared methods.
Theoretical Oxygen Demand
• The Theoretical Oxygen Demand (ThOD) is the determination
of oxygen needed to convert all carbon molecules in pollutants to
CO2, and all NH3 and NO2- to NO3- by balancing equations.
• This calculation is possible on certain rather pure industrial
wastes, but is impractical for most wastewaters, especially those
containing domestic sewage or containing vegetable or animal
Theoretical Oxygen Demand/ Example
In order to determine the ThOD for glycine (CH2(NH2)COOH) using the following
1. In the first step, the organic carbon and nitrogen are converted to carbon dioxide
(CO2) and ammonia (NH3), respectively.
2. In the second and third steps, the ammonia is oxidized sequentially to nitrite and
3. The ThOD is the sum of the oxygen required for all three steps.
• 1. Write balanced reaction for the carbonaceous oxygen demand.
CH2(NH2)COOH + 1.5 02 ->NH3 + 2CO2 + H20.
• Write balanced reactions for the nitrogenous oxygen demand.
NH3 + 1.5 02 -> HNO2 + H20
HNO2 + 0.5 O2 -> HNO3
NH3 + 2 O2 -> HNO3 + H2O.
• Determine the ThOD.
• ThOD= (1.5 + 2) mol O2/mol glycine = 3.5 mol O2/mol glycine
• ThOD = 3.5 mol O2/mol glycine x 32 g/mol O2 / 75 g/mol glycine = 1.49 g O2/g
Relationship between BOD, COD, TOC and ThOD
BODu = 0.9ThOD
Where BODu = ultimate BOD
• BODu = 0.9ThOD because (approximately ten percent of the original organics
remain as non-biodegradable cellular residues after biological oxidation)
BOD5 = 0.77BODu
• BODu is much greater than BOD5 because much of the easily degraded
material would have been removed in the sewage treatment process and many
industrial processes discharge difficult to degrade organic molecules
• For most wastewaters: ThOD = COD
• Stoichiometrically, the COD/TOC ratio should be approximately the molecular
ratio of oxygen to carbon:
The BOD5 to COD ratio for domestic waste and certain biodegradable
industrial wastes can be computed as follows:
Microbiological water quality monitoring is primarily based on tests for
Characteristics of the Ideal Faecal Indicator
• Should be present in wastewater and contaminated water when there are
• Should be present when there is a risk of contamination by pathogens
• Should be present in greater numbers than the pathogens
• Should not multiply in environmental conditions under which pathogens cannot
• The indicator population should correlate with the degree of faecal
• The survival time in unfavorable environmental conditions should exceed that
• Should be more resistant to disinfectants and other stresses than the pathogens
• Should present no health risk
• Should be easy to enumerate and identify by simple methods
• Should have stable characteristics and give consistent reactions in these
This species is a member of the group of faecal coliform
Escherichia coli (E. coli), a rod-shaped member of the
Escherichia coli has the important feature of being highly
specific for the faeces of man and warm-blooded animals.
These bacteria cannot multiply in any natural water
environment and they are, therefore, used as specific
indicators for faecal pollution.
They are generally distinguished from other thermotolerant
coliforms by the ability to yield a positive indole test
within 24 hours at 44.5°C.
E. coli are almost exclusively of fecal origin and their
presence is thus an effective confirmation of fecal
Thermotolerant coliform bacteria
certain members of the group of total
coliform bacteria which are more closely
related to faecal or sewage pollution, and
which generally do not readily replicate in
This group of bacteria is also known as
faecal coliforms, presumptive E. coli, faecal
E. coli, faecal coli, etc.
Thermotolerant coliforms are primarily
used for the assessment of faecal pollution
in waste water and raw water sources.
Detection of faecal streptococci
(Coliform bacteria (total coliforms
• The term "coliform bacteria" refers to a vaguely
defined group of Gram-negative bacteria which
have a long history in water quality assessment.
bacteria are microorganisms that
primarily originate in the intestines of warmblooded animals
• Some of the bacteria included in this group are
almost conclusively of faecal origin, while
other members may also replicate in suitable
• The primary purpose of coliform tests is not to
detect faecal pollution but to screen the general
sanitary quality of treated drinking-water
** Enterococci are facultative anaerobic
organisms. i.e., they are capable of cellular
respiration in both oxygen-rich and
** Sometimes referred to as faecal
streptococci, is a group of bacteria more
closely related to faecal pollution than total
coliforms because most members of this
group do not replicate as readily in water
** Enterococcus spp. took the place
of fecal coliform as the new standard in
USA for water quality at public beaches
** It is believed to provide a higher
correlation than fecal coliform with many
of the human pathogens often found in city
they are not capable of forming
spores, enterococci are tolerant of a
wide range of environmental
conditions: extreme temperature (1045°C) , pH (4.5
high sodium chloride concentrations
• Gram-positive bacteria (those that are stained dark blue or violet by Gram
staining), anaerobic bacteria
• Their spores are more resistant to conditions in water environments, as well as
treatment and disinfection processes, than most pathogens, including viruses.
• Clostridia are sometimes considered as too resistant, and their inclusion in
water quality guidelines as too stringent.
• One of the members of the group, Clostridium perfringens, is like E. coli highly
specific for faecal pollution.
• Clostridia generally occur in lower numbers in waste water than coliform
• Detection methods are relatively expensive and time-consuming.
The coliform index is far from perfect.
Thermotolerant coliforms can survive in water on their own, especially in
tropical regions, so they do not always indicate fecal contamination.
they do not give a good indication of how many pathogenic bacteria are
present in the water,
they give no idea at all of whether there are pathogenic viruses or protozoa
which also cause diseases and are rarely tested for.
Therefore, it does not always give accurate or useful results regarding the
purity of water.
Differ from that of faecal indicators for reasons such as:
Viruses are excreted only by infected individuals, and coliform bacteria by
almost all people and warm-blooded animals.
Numbers of viruses in water environments are generally lower than those of
indicators such as faecal coliforms by several orders of magnitude.
Viruses are excreted for relatively short periods
The structure, composition, morphology and size of viruses differs
fundamentally from that of bacteria
Bacterial indicators such as coliform bacteria have shortcomings as indicators
Unfortunately, tests for viruses are relatively expensive, complicated and time
consuming, and require sophisticated facilities and know-how.
Control of the virological safety of water is based on raw water quality and
specifications for purification and disinfection processes rather than testing of
the treated water
Coliform Bacteria Test
• Multiple Tube Coliform Tests
• Membrane Filter Coliform Test
The purpose is to determine the concentration of a pollutant which can exist in a
body of water that will neither kill a test organism (acute toxicity) nor prevent
reproduction (chronic toxicity) of the organism.
After this determination, an application factor is usually multiplied by the test
results to obtain a permit limit.
Commonly used application factors are 0.01 if the pollutant is cumulative in the
internal organs, and 0.10 if the pollutant is not cumulative.
The most common toxicity tests are for daphnia and fish.
Acute toxicity describes the adverse effects of a substance which result either
from a single exposure or from multiple exposures in a short space of time
(usually less than 24 hours(
Chronic toxicity is a property of a substance that has toxic effects on a living
organism, when that organism is exposed to the substance continuously or
In toxicology, the median lethal dose, LD50 (abbreviation for “Lethal Dose,
50%”), LC50 (Lethal Concentration, 50%) or LCt50 (Lethal Concentration &
Time) of a toxic substance or radiation is the dose required to kill half the
members of a tested population after a specified test duration.
LD50 of a substance is given in milligrams per kilogram of body weight.
Measures such as 'LD1' and 'LD99' (dosage required to kill 1% or 99%
respectively of the test population) are occasionally used for specific purposes.
• is a sample taken at one time in one quantity which is deemed representative of
the flow and pollutant concentration.
• must be taken from a well mixed area to allow all settleable and floatable solids
to be included in the sample.
• is one which is taken proportional to either time or flow.
• A time composite sample takes an equal quantity of sample each period of time.
• To be truly proportional, this type of sample should be taken only when
pollutant concentrations are uniform over the time period in which the samples
• The automatic sampler can be adjusted to either take a discrete sample with
time or to add a certain sized sample to a large container at each time period.
• This sampler can be packed with ice to preserve the sample for biological
• Gravimetric analysis: analysis depends upon weighing solids obtained from the
sample by evaporation, filtration or precipitation
• Volumetric analysis : An example of the use of volumetric analysis is found in
the determination of alkalinity and acidity
• Colorimetric analysis
• Visual methods
• Instrumental methods (Absorptiometer , Spectrophotometer, Flame
photometer, Atomic Adsorption)
• Electrode techniques: ion electrodes for determinations such as NH 4+, NO3-, Ca2+,
Na+, CI-, Br-, F-, etc.
• Automated analysis, remote monitoring and sensing
Water Quality / TYPES OF RECEIVING WATERS
Lakes: is classified as a pool of water, which is trapped behind a natural or
artificial dam that normally causes the pool to be contained
The density of water is greatest at 4°C
colder water tends to sink in a lake
In Summer: Sunlight heats the upper layers of water - the deeper water remains
cold – (thermocline)
the thermocline is a narrow vertical zone between the warmer and colder waters
where a rapid temperature change occurs.
In Fall: the surface of the lake reaches a temperature close to 4°C - a strong wind
will overturn the lake stratification and the lake becomes unstratified
Spring overturn (unstratified)
Oligotrophic: Normal lakes have minimal levels of nutrients are said to be
enriched - Oligotrophic
Eutrophication is the enrichment of water by nutrients; a lake that is enriched is
said to be eutrophic
eutrophic lakes contain large populations of aquatic animals
unenriched lake there is a higher concentration of dissolved oxygen
eutrophic lakes the deeper, colder levels of water are depleted of dissolved
oxygen because of the high BOD caused by decomposition on the lake floor
As natural eutrophication occurs, these bodies of water are slowly enriched and
grow shallower from the immense number of dead organisms
Eutrophication can be markedly accelerated by human activities, and it results
from the enrichment of water by inorganic plant and algal nutrients- most
commonly in sewage and fertilizer runoff.
Rivers and Streams
Rivers are uncontrolled by dams, the water level will be directly proportional to
stormwater and the rivers can have a tremendous variation in flow.
A very slowly moving river can stratify similarly to a lake.
Rivers and streams will tend to re-aerate themselves
In order to aid in pollutant distribution from an outfall, some permits may
require an outfall to discharge at several locations across a river.
Intermittent Streams – Ditches – Estuaries - Saltwater
Intermittent stream is a stream that only flows during wet weather
These streams will have very stringent permit levels if the intermittent streams
contain aquatic life which can exist in intermittent water flow conditions and
would be damaged by pollutant discharge.
Also the permit levels should be controlled by the downstream conditions in a
lake, river or stream.
Ditches are artificially created channels (lined or not)
Like intermittent natural streams, ditches have a zero low flow and stringent
Estuaries are the transition areas between fresh water and salt water and contain
much unique aquatic life.
Saltwater: Oceans, gulfs, etc. are highly saline and contain unique marine
aquatic life. Regulations are gradually being made more strict for saltwater
environments as more is discovered about their sensitive environments.
SIGNIFICANT DETERIORATION OF
• Fish and Aquatic Life
• Domestic and Drinking purposes (Health)
Water quality and health
WHO data give an indication of the magnitude of the problem
• each year over five million people die from water-related diseases
• two million of the annual deaths are of children
• in developing countries 80 per cent of all illness is water-related
• at any one time half of the population in developing countries will be suffering
from one or more of the main water-related diseases
• a quarter of children born in developing countries will have died before the age
of five, the great majority from water-related disease.
• At any one time there are likely to be 400 million people suffering from
gastroenteritis, 200 million with schistosomiasis and 160 million with malaria.
All of these diseases can be water-related although other environmental factors
may also be important.
• Bradley classification system for water-related
Guideline values for verification of microbial quality
Definition: water-borne diseases are diseases caused by the ingestion of water
contaminated by human or animal faeces or urine containing pathogens.
Many bacteria, viruses, protozoa and parasites can cause disease when ingested.
The majority of these pathogens derive from human or animal faeces, and are
transmitted through the faecal-oral route.
both animal and human faeces are threats to human health, human faeces are
generally the most dangerous.
Faecal pathogens can be classified as causing both water-borne and water-washed
4.2 million deaths per year (mostly in children under 5) from diarrhoeal disease
from 1955-1979 dropping to 3.3 million per year from 1980-1989, and 2.5 million
per year from 1992-2000
Examples: Typhoid fever is caused by ingestion of Salmonella typhi bacteria –
Hepatitis A and E
Definition: water-washed diseases are diseases caused by inadequate use of
water for domestic and personal hygiene
Examples: Soil-transmitted helminths: ascaris, hookworm الديدان الخطافةand
whipworm ( الديدان السوطيةTrichuris trichiura).
Acute Respiratory Infections: Acute respiratory infections (ARI) including
pneumonia (an inflammatory condition of the lung )ذات الرئةare responsible for
19% of total child deaths every year.
Skin and eye diseases: Trachoma is the world’s leading cause of preventable
blindness: about 6 million people are blind due to trachoma, and more than 10%
of the world’s population is at risk.
Ringworm (tinea) is an infectious disease of the skin, scalp فروة الرأسor nails.
Flea , البرغوثlice , القملmite and tick-borne diseases: Scabies is caused by the
microscopic mite Sarcoptes scabei and characterized by intense itching. Scabies
spreads rapidly, and causes an estimated 300 million cases each year.
Water-based diseases and Water-related diseases
Water-based diseases: are infections caused by parasitic pathogens found in
aquatic host organisms.
Eg. Schistosomiasis is a major parasitic disease in tropical and sub-tropical
regions, second only to malaria in terms of socio-economic and public health
Water-related diseases; are caused by insect vectors which either breed in
water or bite near water.
not directly related to drinking-water quality
The most common vector insects are mosquitoes and flies like:
– Mosquito-borne diseases (malaria - yellow fever)
– Fly-borne diseases (onchocerciasis (river-blindness) - trypanosomiasis
(West African sleeping sickness)
Morbidity and mortality rates of some important water-related
)diseases (after WHO, 1995
• every groundwater investigation involves a determination of both the quantity
of water available and the quality of the water
• The graphical methods used to facilitate the interpretation and presentation of
chemical analysis. Types of Graphical representations:
• Box and Whisker Plot - Multiple Parameters / Multiple Stations
• Depth Profile Plot
• Frequency Histogram
• Ludwig-Langelier Plots
• Pie Charts
• Piper Diagrams
• Radial Diagrams
• Scatter Plots
• Schoeller Plots
• Stiff Diagrams
• Site Map Diagrams
• Ternary Diagrams
• Time Series Plots - Multiple Stations / Multiple Parameters
• Wilcox Diagram
Graphical Methods / Box and Whisker Plot - Multiple
Parameters and Multiple Stations
• The Box and Whisker - Multiple Parameters plot displays a statistical
summary of multiple measured database parameters, at a selected station
• The Box and Whisker - Multiple Stations plot displays a statistical
summary of any measured database parameter, at multiple station locations.
The plot displays the following statistical analyses:
• The minimum measured value;
• Q1: the first (lower) quartile (25th percentile): 25% of the data lie below this
• Q2: the second quartile (Median): 50% of the data lie below this value;
• Q3: the third (upper) quartile (75th percentile): 25% of the data lie above
• The maximum measured value
Graphical Methods / Box and Whisker Plot - Multiple
Parameters and Multiple Stations
Depth Profile Plot
the plot displays the change of a measured parameter over a measured
The plot can be used to plot all samples in the open database or selected
The Durov diagram plots the major ions as percentages of milli-equivalents in
two base triangles.
The total cations and the total anions are set equal to 100% and the data points
in the two triangles are projected onto a square grid which lies perpendicular to
the third axis in each triangle.
This plot reveals useful properties and relationships for large sample groups.
The main purpose of the Durov diagram is to show clustering of data points to
indicate samples that have similar compositions.
• used to check the number of populations within a given range of measured
• The frequency of samples within the given ranges can be plotted according to
percentages or numbers of samples.
• The range of values can be customized up to 10 or more groups and the
individual samples can be identified at the associated value along the x-axis.
Suitable groupings of cations and anions are selected and plotted as
percentages of milli-equivalents.
By convention, the sums of the selected cations are plotted on the y-axis, and
the sum of the selected anions are plotted on the x-axis.
Each axis ranges from 0 to 50 meq%.
All major elements can be displayed in one plot.
it displays relative ratios rather than absolute concentrations.
The Ludwig-Langelier diagram can be used to plot all samples in the open
database or selected sample groups.
Is used to plot the concentrations ratio of the major ions (or any combination of
parameters) for individual samples.
• is used to graphically compare the concentration ratios of several measured
parameters for several different samples.
• The color and patterns used to identify each parameter are customizable
is a graphical representation of the chemistry of a water sample or samples.
The Piper diagram plots the major ions as percentages of milli-equivalents in
two base triangles.
The cations and anions are shown by separate ternary plots.
The apexes of the cation plot are calcium, magnesium and sodium plus
The apexes of the anion plot are sulphate, chloride and carbonate plus hydrogen
The two ternary plots are then projected onto a diamond.
The diamond is a matrix transformation of a graph of the anions
(sulfate + chloride/ total anions) and cations (sodium + potassium/total cations).
The total cations and the total anions are set equal to 100% and the data points in
the two triangles are projected onto an adjacent grid.
This plot reveals useful properties and relationships for large sample groups.
The main purpose of the Piper diagram is to show clustering of data points to
indicate samples that have similar compositions.
The Piper diagram can be used to plot all samples in the open database or
selected sample groups.
Figure 1 from Kehew (2001).
Water analyses plotted on a
Cation percentages in meq L-1
plotted on the left triangle, and
Anion percentages in meq L-1
plotted on the right triangle.
• Radial diagrams are plotted for individual samples as a method of graphically
comparing the concentrations of measured parameters for several individual
• The shape formed by the Radial diagrams will quickly identify samples that
have similar compositions and are particularly useful when used as map
symbols to show the geographic location of different water facies
the most simple initial approach to the interpretation of geochemical data.
Single plots of ion relationship and parameters that show significant data can be
easily created and patterns are quickly identified and easily understood.
Both normal scale and log scales are supported for the x and y axes and
multiplication factors can be applied to either the x or y parameter.
Parameter ratios and sums may also be included for either axes.
• These semi-logarithmic diagrams were developed to represent major ion
analyses in meq/l and to demonstrate different hydrochemical water types on
the same diagram.
• This type of graphical representation has the advantage that, unlike the trilinear
diagrams, actual sample concentrations are displayed and compared.
• Up to 10 different parameters can be included along the x-axis
Is used to display the major ion composition of a water sample.
A polygonal shape is created from four parallel horizontal axes extending on
either side of a vertical zero axis.
• Cations are plotted in milliequivalents per liter on the left side of the zero axis,
one to each horizontal axis, and anions are plotted on the right side.
• Stiff patterns are useful in making a rapid visual comparison between water from
Stiff diagrams can be used:
• 1) to help visualize ionically related waters from which a flow path can be
• 2) if the flow path is known, to show how the ionic composition of a water body
changes over space and/or time.
• When comparing Stiff diagrams between different waters it is important to prepare
each diagram using the same ionic species, in the same order, on the same scale.
• to convert the mass concentration mg/L to an equivalent concentration
(mass conc.)*(ionic charge)/(molecular weight)=(equivalent conc.)
• Example, a water with a calcium concentration of 120 mg/L would have the
following calcium equivalent concentration:
(120 mg/L) * (2 meq/mmol) / (40 mg/mmol) = (5 meq/L)
Pine Creek, CDA Valley, Idaho
An example of a Stiff diagram drawn
for mine waters from the Pine
Creek district, Coeur d’Alene
The anions are mostly dominated by
sulfate, with lesser bicarbonate,
whereas the cations are dominated
by calcium and magnesium.
Ion concentrations in meq L-1 are plotted on the
Cations are plotted to the left, anions to the
right, of a vertical axis.
The data are plotted in four rows and the points
are connected to form a polygon.
Advantage: each water type produces a distinct
Disadvantage: each analysis requires its own
plot; only a limited number of data can be shown
on a single plot.
Site Map Diagrams
• Sample locations can be displayed on an X-Y graph and a detailed site maps
can be imported from AutoCAD DXF files to provide a familiar point of
reference when you are analyzing sample data.
• the map plot can be used to display the location of different water types, or the
symbols can be scaled in color or in size according to the concentration of a
selected measured element
is used to identify trends and relationships between groups of samples.
it is easier to understand than Piper or Durov diagrams since it involves fewer
parameters and does not project data points onto a grid.
Like the Piper diagram, the Ternary diagram plots the ions as percentages of
their concentration values.
is not limited to using only meq units.
Time Series Plots - Multiple Stations
• This Time Series plot displays the evolution of a physical or chemical
parameter for multiple sampling locations, as a function of time.
• This plot is a standard technique for interpreting hydrochemical and
hydrogeological processes in natural waters.
Time Series Plot - Multiple Parameters
• This Time Series plot displays the evolution of multiple chemical or physical
parameters for a given sampling point as a function of time.
Can be used to quickly determine the viability of water for irrigation purposes.
The Wilcox plot is a simple scatter plot of Sodium Hazard (SAR) on the Y-axis
vs. Salinity Hazard (Cond.) on the X-axis.
The Conductivity (COND) is plotted by default in a log scale.
The Wilcox plot has the following sections:
C1: Low (0-249)
C2: Medium (250-749)
C3: High (750-2249)
C4: Very High (2250-5000)
The SAR values are divided into the following categories:
S4: Very High