The document discusses water quality and drinking water standards. It provides information on various types of water quality parameters including physical, chemical, and biological characteristics. It describes factors that affect water quality such as contamination from living organisms, solids, and dissolved materials. It also outlines primary and secondary drinking water standards from organizations like the WHO and EPA, which establish limits for parameters to protect human health and aesthetic quality. Regular water quality monitoring is emphasized to ensure standards are being met.

1. Water quality: Water in pure form is not found in nature. It is a best solvent and attract
a lot of impurities. Rain water is assumed to be pure, even water vapor condensing in
the air Contains solids, dissolved gases and salts. As it touch surface, percolating into
the soil or runoff occurs, some contaminants may be removed while new one will be
added. The materials found in water are living organisms, solids, dissolved organic
and inorganic. Some of these are harmless and desired for health while others are
harmful. Drinking water or potable water is water of sufficiently high quality that it can
be used without risk of immediate or for long term safe for drinking , pleasant in taste
and suitable for domestic use. Such water may be unsuitable for some industrial use.
Contaminated or Polluted water is one which contains suspended or dissolved
materials which makes it unsuitable for its intended use. Two types of criteria is used
for for drinking water quality. One is the World health Organization Guidelines and
another is the Standards adopted a number of countries.
World Health Organization Guidelines: These are the guidelines related to human
health and is advisable for developing as well as for developed counties for adaptation.
There is no compulsion for a country either to adopt it or not. It help member countries
of WHO to adopt it and provide safe water to community.
Standards : A number of countries developed their own criteria for drinking water.
This criteria is termed as standards. In these standards some are adoptable by the
agency providing water and other are advisable.

2. Drinking water standards are of two categories. Primary standards and Secondary
standards
Primary Standards: The standards which are enforceable by Govt. Agency for protection
of human health are known as primary standards. These standards specify the Maximum
Contaminants Levels (MCLs) based on health related criteria for drinking water . In setting
the MCLs the authorized agency is to balance the public health benefits of the standards
against the technology available and economically feasible. The water supply authorities
who violate these standards are to face punishment. e.g. Arsenic 0.05 mg/L; Mercury
0.002 mg/L; Beryllium 0.001 mg/L
• Secondary Standards. These standards are unenforceable guidelines based on aesthetic
like color, taste and odor for drinking water. It is up to the water supply agency either to
adopt it or not. Such sets of unenforceable levels are known as Maximum Contaminant
Level Goals (MCLGs). These goals are set at levels that present no known health
effects, including a margin of safety , regardless of technological feasibility or cost. Like;
Arsenic 0 mg/L; Mercury 0.002 mg/L; Beryllium 0. mg/L

3. Drinking Water Standards of US EPA
Primary Standards MCL (maximum contaminant level)
Contaminant Limit
• Total coliforms (av. Number/ 100 mL) 1
• Total coliforms (max number/ 100 mL) 5
• Turbidity (ntu) 1-5
• Inorganic chemicals (mg/L)
• Arsenic 0.05
• Cadmium 1.0
• Chromium 0.01
• Fluoride 0.07-
2.4
• Lead 0.05
• Mercury 0.002
• Nitrate (as N) 10.00
• Selenium 0.01
• Silver 0.05
• Radionuclides (pCi/L)
• Gross alpha 15
• Ra-226 + Ra-228 5
• Gross beta 50
• H-3
20,000
• Sr-90 8
• Organic Chemicals (μg/L)
• Endrin 0.2
• Lindane 40
Contaminant Limit
• 2,4_D 100
• 2,4,5-TP 10
• Trihalonethanes 100
• Benzene 0.05
• Carbon trtrachloride 0.05
• 1,2 Dichloroethane 0.05
• Trichloroethylene 0.05
• Para-dichlorobenzene 0.75
• 1,1 Dichloroethylene 0.07
• 1,1,1 Trichloroethane 2.0
• Vinyl chloride 0.02
• Secondary Standards RCL
(recommended contaminant level)
• Contaminant Limit
• Chloride 250 mg/L
• Color 15 units
• Copper 1 mg/L
• Iron 0.3 mg/L
• Manganese 0.05 mg/L
• Odor 3 TON
• pH 6.5-8.5
• Sulfate 250 mg/L
• Total Dissolved Solids 500 mg/L
• Zinc 5 mg/L

4. • Monitoring: water supply schemes are required to provide safe drinking water to community.
There are standards and guidelines established by various countries/organizations that
guarantee provision of safe water free of contaminants that have negative health effect when
using such water. To minimize negative impact of impurity in drinking water regular sampling and
analyzing of water quality is essential. The purpose of water quality monitoring is to check the
physical, chemical and biological characteristics either they are suitable for intended purposes
like drinking, swimming, irrigation ,industrial purposes or not. To regular analyze samples of
water from different sources like surface or ground water and compared it with available
standards are known water quality monitoring. Monitoring is essential for continuous record for
department. If there is any contaminant or a group of contaminants present in drinking water
then mitigation measures are required to eradicate or minimize these contaminants. A regular
monitoring is required to check that water supply system meets public health standards or not.
Monitoring requirements vary for the following reasons.
• (i) Regulations of a country drinking water agencies specify samples locations and acceptable analytical
methods. (ii) Identify whether the quality of water is fulfilled the requirements used for intended purpose or
not. (iii) The frequency of monitoring for a contaminant may vary based on the type of water source. (iv)
Surface water system need monitoring more frequently than ground water because of the occurrence of
contaminants are more variable over time.(v) characterize waters and identify changes or trends in water
quality over time (vi) identify specific existing or emerging water quality problems. The source of water if
do not detect or detect at low levels can monitor less frequently.

5. Physical, Chemical and Biological Quality/Characteristics of water/ wastewater
Suspended: 1.0 – 100 μ; colloidal 100-3μ -1 μ : Dissolved 10-3 μ – 10-5 μ
Physical characteristics: Physical characteristics are those characteristics that respond to the
senses of sight, touch , smell or taste. Suspended solids, turbidity, color, taste and odor and
temperature are physical characteristics.
Suspended Solids: Solids suspended in water consists of inorganic or organic particles or of
immiscible liquids. Inorganic solids like clay, silt and other soil constituents are common in surface
water. Organic materials like plant fibers and biological solids (bacteria, algal cells etc) are common
constituents of surface water. These materials are often natural contaminants resulting from the
erosive action of water flowing over surfaces. Other suspended materials may result from human use
of water. Domestic wastewater usually contains large quantities of suspended solids. Industrial use of
water may result variety of suspended impurities of organic and inorganic nature. Immiscible liquids
like grease, oil are often found in wastewater.
Impacts: Suspended materials are objectionable in water. It is aesthically displeasing and provides
adsorption sites for chemical and biological impurities. Some of the Suspended organics may be
degraded biologically, resulting in objectionable byproduct. Biologically active suspended solids may
include pathogenic microorganisms.
Use: suspended solids parameter is used to measure the quality of wastewater influents, to monitor
several treatment processes, and to measure the quality of the effluents. EPA standards are 30 mg/l .

6. Turbidity
Turbidity is a measure of the extent to which light is either absorbed or scattered by suspended
particles in water. As the adsorption and scattering processes are influenced by size and surface
characteristics of the suspended materials, turbidity is not a direct quantitative measurement of
suspended solids. Turbidity in surface water result from the erosion of colloidal material like clay,
silt, rock fragments, vegetable fibers, soap, detergents, household and industrial activities and
microorganisms.
Impacts: The colloidal particles and biological organisms associated with turbidity provides sites
for adsorption of chemicals that may be harmful or cause undesirable taste and odors.
Disinfection of turbid water is difficult because of the adsorptive characteristics of some colloids
as well as provide shield to organisms from the disinfectants.
In natural water bodies, turbidity interfere with light penetration. Also the turbid particles
accumulation in porous streams result in sediment deposit that adversely affect the flora (plant)
and fauna (animal) present in the streams.
Unit: Nephelometry turbidity units (NTU) or Formazin turbidity unit (FTU) are used. According to
EPA drinking water MCL is 1.0 FTU.

7. Color
Pure water is colorless, but water in nature is often colored by foreign substances. Water whose
color
is due to suspended matter is known as apparent color, while due to dissolved particles is true color.
Sources: Water picks up tannins and humic acid from organic matter like plant leaves, weed or wood
Caused yellowish-brown hues. Iron oxides cause reddish water and manganese oxides cause brown
or blackish water. Industrial waste from textile and dyeing operations pulp and paper production, food
processing, chemical production and mining, refining and slaughter house operations may add
substantial colors to water in receiving steams.
Impacts: Colored water is not aesthetically acceptable to the general public. Consumers tend to
choose clean, non colored water of poor quality over treated potable water supplies with an
objectionable color. Highly colored water is unsuitable for laundering, dyeing, paper making,,
beverage
and dairy production. Thus color of water affects the organic compound causing true color exert
chlorine demand and thereby seriously reduce the effectiveness of chlorine as disinfectant. Some
compounds of naturally occurring organic acids and chlorine formed Trihalomethanes (THMs)
carcinogenic in nature.

8. Taste and odor and Temperature
A number of substances with which water comes into contact in nature or during human use may
impart taste and odor. These includes minerals, metals and salts from the soil, end products from
biological reactions, and constituents of wastewater. Inorganic materials produce taste Without
odor. Alkaline materials imparts a bitter taste to water, while metallic salts give a salty taste.
Organic material, produce both taste and odor. Biological decomposition of organics may also
result in taste and odor producing liquids and gases in water.
Impacts: Taste and odor are displeasing for various reasons, as water is to be tasteless and
odorless. Consumer prefer to use tasteless, odorless water that might pose more health threat.
Temperature: It is one of the most important parameter in natural surface water system. Water
temperature plays an important role in biological species present and their rate of activity.
Temperature has an effect on most chemical reactions that occur in natural water system. It also
have a pronounced effect on the solubility of gases.
Sources: The temperature of natural water bodies response to many factors, the ambient
temperature being the most effective one. Generally, shallow water bodies are more affected by
ambient temperatures than the deeper bodies. The use of water industries for dissipation of waste
heat and discharge of the heated water to receiving water bodies increase the temperature.
Impacts: At lower temperature the biological activity like utilization of food supplies, growth
reproduction etc. is slower. If temperature is increased biological activity also increase. The
viscosity of water increase with decreasing temperature. Max. density of water occurs at 40C.

9. Chemical characteristics of water
Chemical parameters are related to the solvent capabilities of water. Total Dissolved Solids (TDS)
alkalinity, pH, hardness, Organic and inorganic dissolved impurities are the chemical characteristics.
TDS: The materials left in water after filtration for the suspended solids are dissolved
solids. This materials are left as a solid residue upon evaporation of the water. TDS is expressed in
mg/ l. The organic fraction can be measured by heating the TDS at 550± 50 C0. The organic residues
will be evaporated while inorganic residues will be converted into ashes. TDS = Organic + inorganic
thus organic residues = TDS - inorganic
Sources: Dissolved solids result from solvent action of water on solids., liquid and gases. Dissolved
solids may be either organic like decay products of vegetation, from chemicals and from organic
gases. The inorganic dissolved in water are minerals, metals and gases which come in contact with
these substances in atmosphere on surface and within the soil. Materials from decay products of
vegetation, chemicals and gases are organic sources.
Impacts:- Dissolved minerals, gases and organic constituents may be producing displeasing color,
taste and odor. Some chemicals may be toxic and carcinogenic.
Alkalinity: Alkalinity is the quantity of ions that will react to neutralize hydrogen ions. Thus it is a
measure of the ability of water to neutralize acids.
Sources: The major constituents of alkalinity are hydroxyl (OH-), Carbonate (CO3 ) and bicarbonate
(HCO3 ). These compounds result from the dissolution mineral substances in the soil and
atmosphere.

10. Inorganic and organic contaminants
Inorganic contaminants: The sources of trace metals associated with the natural processes of
chemical
Weathering, soil leaching and with human activities like mining and manufacturing processes.
These materials are generally toxic. Arsenic a by product of copper and lead smelting, also a
component
of some agricultural insecticides, present widely distributed in water at low concentration. Arsenic is a
well known poison, carcinogenic in nature and can be fatal in high doses . Cadmium a metal toxic
released to atmosphere from industries of battery producers and electroplaters. Cadmium is taken up at
all levels of food chain from microorganisms to humans. Human consumption of leafy vegetables, fish,
and drinking water is the usual method by which cadmium enter our bodies. Its effect on human bodies
are in form of lungs, kidney problems and joint pains. It is possibly a carcinogenic. Fluoride is the
naturally occurring form of fluorine, found in soil and rocks. Low concentration of fluoride caused dental
caries in children ‘s teeth. The optimum dose makes teeth more resistant to decay, at high concentration
cause fluorosis (discoloration) and loss of teeth. Lead and mercury are associated with chronic effects
on nervous system. Nitrate can interfere with oxygen transfer in the blood of Infants and caused
Methemoglobinemia or blue baby disease. Selenium a trace metal naturally occurring in soils derived
from sedimentary rocks. Surface water and ground water having variable concentration of selenium. It
can produce gastrointestinal and dental problems, while silver is toxic in high dose.
Short duration problem is acute, longer is chronic and change of tissues are carcinogenic

11. Alkalinity
In addition to their mineral origin, these substances can originate from CO2 present in atmosphere and
microbial decomposition of organic materials. The reaction are
CO2 + H2O ↔ H2 CO3 (i) H2 CO3 ↔ H+ +HCO3 (ii) (bicarbonate) HCO3 ↔ H+ +CO3 (iii) (carbonate)
CO3 + H2O ↔ HCO3 + OH- (iv) (hydroxyl or hydroxide)
The relative quantities of each are a function oh pH. Hydroxyl ion concentration are significant
at pH≥ 10, the carbonate concentration below 8.3 are not significant. The bicarbonate concentration
are usually in the range of pH values of 4.5 to 8.3.
pH : pH is a measure of the free hydrogen ion (H+) concentration in water. Water and other chemicals
in solution will ionized to a greater or lesser degree. The ionization reaction of water may be written
as
HOH ↔ H+ + OH- .The concentration of H and OH can be written as [H][OH] = Kw = 10-14 at 20 C0
Taking log of both sides Log [H] + Log [OH] = -14 let ( – log )= p then pH + pOH = 14. pH= -log[H+].
In neutral condition [H] = [OH] ; hence pH = pOH = 7. Thus pH is the negative logarithm of hydrogen
ion concentration. Increasing acidity leads to higher values of [H]; thus to lower values of pH. Low pH
is associated with acidity, high pH with causticity (alkalinity). Acceptable value for drinking water is 6.5
to8.5
pH( Hydrogen ion concentration)
1----------------------------7------------------------14
Acidic Basic
• Signifance:- chemical coagulation disinfection water softening corrosion control

12. Hardness
The concentration of multivalent metallic cations (Ca2 +, Mn2+, Sr2 +, Al3 + ) in solution is hardness. The
common anions are bicarbonate (HCO3, carbonate (CO3 ), Chloride (Cl - ), sulfate (SO4) and NO3)
Hardness caused to prevents leathering (foam) still water becomes soft. Ground water usually have
more hardness as compared to surface water. It is not necessary to remove hardness of water for
drinking purposes, but for industrial utilization hardness removal is essential, because the hard water
are likely to cause Scaling trouble in boilers and in hot water pipes. The other impacts are the
precipitates formed by hard water adhere to the surfaces of tub, sink, dishwasher and other
containers. Types of Hardness: Two types of hardness are Temporary and Permanent Hardness.
Temporary Hardness:- If HCO3, and CO3 of Ca and Mg are present in water, such hardness is
Carbonate or temporary hardness. It can be removed by boiling of water.
Permanent Hardness:-The presence of sulphate, chloride and nitrates of calcium and magnesium is
Permanent or non-carbonate hardness. It cannot be removed by boiling of water. Some chemicals
like
lime soda or activated carbon or ion exchange process can be used to remove permanent hardness.
Generally surface water softer than G.W.
Soft water = 0-75 mg/L as calcium carbonate; Moderately Hard = 75 -100 mg/L as CaCO3.
Hard water 100 - 300 mg/L asCaCO3 and very hard water >300 mg/l as CaCO3.
The maximum recommended standard for drinking water is 500 mg / l

13. Natural Process of Hardness
. In natural process as rain water enters the
top soil, the respiration of
microorganisms increases the CO2
content of the water. The CO2 reacts
with water to form carbonic acid
(H2CO3).The lime stone (CaCO3 and
Mg CO3) reacts with carbonic acid
forming calcium carbonate [Ca(HCO3)2]
and magnesium bicarbonate
[Mg(HCO3)2]. The Calcium and
Magnesium carbonate are insoluble in
water , while bicarbonate are soluble in
water causing hardness in water.
Similarly the Gypsum (CaSO4 ) and Mg
SO4 may also cause hardness of water
present in subsoil layers.
Rain
Top soil Bacterial Action CO2
Sub soil CO2 + H2O H2CO3
Lime stone CaCO3(s)+ H2CO3 Ca (HCO3)2
MgCO3 (s) + H2CO3 Mg (HCO3)2

14. Inorganic contaminants
Inorganic contaminants: The sources of trace metals associated with the natural processes of
chemical
Weathering, soil leaching and with human activities like mining and manufacturing processes.
These materials are generally toxic. Arsenic a by product of copper and lead smelting, also a
component
of some agricultural insecticides, present widely distributed in water at low concentration. Arsenic is a
well known poison, carcinogenic in nature and can be fatal in high doses . Cadmium a metal toxic
released to atmosphere from industries of battery producers and electroplaters. Cadmium is taken up at
all levels of food chain from microorganisms to humans. Human consumption of leafy vegetables, fish,
and drinking water is the usual method by which cadmium enter our bodies. Its effect on human bodies
are in form of lungs, kidney problems and joint pains. It is possibly a carcinogenic. Fluoride is the
naturally occurring form of fluorine, found in soil and rocks. Low concentration of fluoride caused dental
caries in children ‘s teeth. The optimum dose makes teeth more resistant to decay, at high concentration
cause fluorosis (discoloration) and loss of teeth. Lead and mercury are associated with chronic effects
on nervous system. Nitrate can interfere with oxygen transfer in the blood of Infants and caused
Methemoglobinemia or blue baby disease. Selenium a trace metal naturally occurring in soils derived
from sedimentary rocks. Surface water and ground water having variable concentration of selenium. It
can produce gastrointestinal and dental problems, while silver is toxic in high dose.
Short duration problem is acute, longer is chronic and change of tissues are carcinogenic

15. Organic Contaminants
• Organic impurity in water may be either natural or synthetic. Natural contaminants are usually
caused color, taste and odor, while synthetic are considered as a potential threat to living
organisms including human itself. The organic materials present in water may be changed by
treatment processes, and become dangerous or unpleasant. The three groups of organic
contaminants are;
• Chlorinated Hydrocarbons (Synthetic Organic Chemicals (SOCs)). SOCs are compounds used
in the manufacture of a wide variety of agricultural and industrial products. They include
pesticides and herbicides. These organic materials are persistent both in nature and within
human body. The common example of these SOCs are endrin, lindane, methoxychlor and
toxaphene as insecticides, while 2, 4-D, and 2, 4, 5-TP are herbicides. Lab. test shown its
carcinogenic effect.
• Volatile Organic Chemicals (VOCs): These are synthetic chemicals that readily vaporize at room
temperature. These include degreasing agents, paints thinners, glues, dye, benzene, carbon
tetrachloride, and vinyl chloride etc. These chemicals are widely distributed in water. These
chemicals are expected to be carcinogenic in nature.
• Trihalomethanes (THMs): These are the byproduct of water chlorination process or enter in water
from industrial processes. When natural organic substances from decay vegetation, like humic
acid and fulvic acid are treated with chlorine, bromine or iodine THMs are resulted. They include
chloroform (CHCl3), bromodichloromethane (CHBrCl2), dibromodichloromethane(CHBr2Cl), and
Bromoform CHBr3). THMs are carcinogenic in nature and their presence in drinking water is
undesirable.

16. Biological Bacteriological water Quality
Aquatic organisms range in size from smallest single-cell microorganism to largest fish. All these biological
community are the water quality parameters upto certain extent, A water body having large number of aquatic
species indicate good quality, while less number show low quality. Some organisms can be used as an indicator of
the presence of pollutants like; Pathogens: A Pathogen is an agent that cause infection in a living host. These
organisms are not native to aquatic system and usually require an animal host for growth and reproduction. It can
be transported by water system and reach to human/animal causing disease. It capable of infecting or transmitting
disease to human known as water borne disease. Following are the water borne Pathogen.
Bacteria: Bacteria is a single cell microorganism, found in water, wastewater, soil, air and milk. Bacteria are
reproduce by binary fission and are characterized by their shape, size and structure. The common shape of
bacteria
are spherical (cocci), singular (coccus) and cylindrical or rodlike (bacilli).Most bacteria range in size from 0.5 to
5.0 μm long and 0.3 – 1.5 μm wide. The Cocci is about 0.1 μm in diameter.
Viruses. The smallest biological structure that can be seen only by electron microscope. Its size range from 10 to
250 nm. Viruses are unique in that they contain no internal enzymes and therefore can not grow or metabolize on
their own. They are obligate parasites, infecting the tissues of bacteria, plants and animals, including human
beings. Example of of pathogenic viruses are small fox, infectitis hepatitis and influenza. Viruses are not survive
out side the host. Their reproduction or replicate take place within their specific host cells.
Protozoa. Protozoa may be pathogenic or non pathogenic. It is a complete self-contained organisms that can be
free living, or parasitic organism. Protozoa are widely distributed in natural water. Protozoa infections are usually
gastrointestinal disorder of mild order.