Water sources and water quality

1. UNIT II : WATER SOURCES & WATER QUALITY
E N V I R O N M E N T A L E N G I N E E R I N G , S E M E S T E R I V M o d u l e T u t o r : P h u r b a T a m a n g

2. Highlights: Water Quality Parameters, Water Quality Standards,
T u t o r : P h u r b a T a m a n g
A s s o c i a t e L e c t u r e r
M . T e c h E n v i r o n m e n t a l E n g i n e e r i n g , I I T R O O R K E E
D e p a r t m e n t o f C i v i l E n g i n e e r i n g & S u r v e y i n g
J i g m e N a m g y e l E n g i n e e r i n g C o l l e g e
UNIT II: WATER SOURCES & WATER QUALITY

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Quality and quantity of surface water and its usefulness for public water supplies
- The quantity of available surface water is dependent upon rainfall. Though sufficient
and considerable rainfall, it is not uniformly and regularly spread throughout the year.
Thus the available flow in the stream or channel or a river may be too high to be
controlled or may be too less to fulfill the demand.
- Storage reservoirs, therefore, provide good means of storing and utilizing rain water.
- Quality: The rain water, though pure in the beginning, get considerably polluted till it
reaches the river streams. The gases, dusts, etc., from the atmosphere, get added to the
rain water till it reaches the ground, from where onwards it flows on the earth’s surface
and also through drains and channels which add a lot of organic and inorganic impurities
to it.
- The surface supplies are generally contaminated and cannot be used with minor
treatment or without any treatment. They need building up of proper purification plant and
other connected works before being used for public supplies.
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
UNIT II: WATER SOURCES AND WATER QUALITY

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Quality and quantity of sub-surface water
- The water which gets stored in the ground water reservoir through infiltration is known
as underground water.
- This water is generally pure, because it undergoes natural filtration during the
percolation through the soil pores.
- However they are generally rich in dissolved salts, minerals, gases etc. The extent of the
minerals and salts present in the ground water depends upon location, geology and land
use practices in the area.
Groundwater can contain:
- Dissolved salts: Calcium, Magnesium, Sodium and Potassium
- Heavy Metals: Arsenic, lead and mercury
- Hydrogen Sulphide gas: Cause of a rotten egg smell
UNIT II: WATER SOURCES AND WATER QUALITY
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1

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Water Quality Concerns
- The human right to water entitles everyone without discrimination to sufficient,
safe, acceptable, physically accessible and affordable water for personal and
domestic use.
- While quality of supplied water should ensure public health safety ( water free
from pathogens and chemicals ) the water abstracted from the source may not be
of usable quality in its natural state.
- A municipal water supply system needs to meet standard drinking water quality
standards ( Bhutan Drinking Water Quality Standard (BDWSQ) and World Health
Organization Standard )
- As drinking water does not meet these standards, thus treatment of water is
essential before it is made available to the public.
UNIT II: WATER SOURCES AND WATER QUALITY
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1

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Sources of water pollution
Point source of water pollution:
- Pollution that comes from the identifiable sources, such as factory, sewage
treatment plant, pipe or drain etc. It is typically easier to identify, monitor and
regulate.
- Example: Factory that releases chemicals into a river can be easily identified and
regulated.
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
UNIT II: WATER SOURCES AND WATER QUALITY

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Sources of water pollution
Non- Point source of water pollution:
- Pollution that enters water bodies of water from multiple sources over a large
area, rather from a single source.
- It can not be traced to a single location (source).
Example:
- Agriculture Runoff : One of most significant non point sources of water pollution.
Fertilizers, pesticides, and herbicides used in farming can wash off into streams
or rivers.
- Urban Runoff: Stormwater from urban areas also contribute to water pollution.
- Construction site runoff
- Mining activities
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
UNIT II: WATER SOURCES AND WATER QUALITY

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Sources of water pollution
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
UNIT II: WATER SOURCES AND WATER QUALITY

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Nature of Water Pollutants
On the basis of pollutant sources:
- Industrial, Agricultural, Urban and Natural Pollutants
On the basis of physical and chemical characteristics:
- Physical pollutant : In terms of color, sediments, etc.
- Chemical pollutant : In terms of different chemicals present in water.
- Biological pollutant: In terms of bacteria, virus and pathogens present in water.
On the basis of degradation nature:
- Degradable pollutant (reactive) – Pollutant that can break down or degrade overtime
through natural processes such as biological or chemical processes.
- Examples: biodegradable waste, paper products, etc.
- Non-degradable pollutant (non-reactive) – Does not degrade overtime and persist in the
environment for a long time. Examples: plastics, pesticides, heavy metals, etc.
UNIT II: WATER SOURCES AND WATER QUALITY
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1

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Routes of Exposure for Water Pollutants
Typically, an exposure to water pollutants can happen either from ingestion or dermal.
- Ingestion ( oral route ) exposure – It can occur via consumption of contaminated water
directly or other food items prepared using contaminated water.
- Dermal (skin route) exposure – It can result from skin contact with contaminated water
during bathing, washing, swimming, etc.
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
UNIT II: WATER SOURCES AND WATER QUALITY

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Quality of Water
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
Physical Appearance may not be the only criteria to
evaluate the quality of water
UNIT II: WATER SOURCES AND WATER QUALITY

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Water Quality Assessment
The assessment of water quality is carried out through monitoring/analyzing Water
Quality Parameters, which show it’s Physical, Chemical and Biological properties .
Some of the common water quality parameters include:
- Physical parameters:
Temperature, Colour, Odour, Turbidity, Solids ( Total, suspended, dissolved, fixed
and volatile )
- Chemical parameters: pH, Acidity, Alkalinity, Hardness, Nutrients ( Nitrogen and
Phosphorus ), Heavy metals, Dissolved Oxygen (DO), Chemical Oxygen Demand
(COD), Biological Oxygen Demand (BOD)
- Biological/Microbial parameters: Most Probable Number ( MPN ) and Total and
Fecal Coliform
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
UNIT II: WATER SOURCES AND WATER QUALITY

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Water Quality Parameters (Physical)
- Temperature: Determines the solubility of pollutants in water. Increases the
biological and reaction rates. It is measured using thermometers ( Celsius, Kelvin,
Fahrenheit )
- Conductivity or Electrical Conductivity: Ability of water to carry an electrical
current. Pure water is poor conductor of electricity and water shows significant
conductivity when dissolved salts are present ( generally, directly proportional to
the amount of salts dissolved in water). It is measured using conductivity sensors
and expressed as siemens/meter.
- Colour: It is an essential from the aesthetic point of view. Colour in water is often
caused by organic substances such as algae or humic compounds. The colour
could be Apparent (caused by suspended matter) or true (caused by dissolved or
colloidal solids). Measured by tintometer.
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
UNIT II: WATER SOURCES AND WATER QUALITY

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Water Quality Parameters (Physical)
- Odor (smell): Odor in water is objectionable. Pure water is odorless but may
acquire odour when some substances are dissolved. Decayed organic substances
give fouling smell while inorganic substances give earthly smell. Odour is
measured through Threshold Odour Test, where dilution factor is determined to
make the water odorless.
- Turbidity: It is an optical property, describing the clarity or haziness of the water
caused by the presence of very fine suspended or colloidal particles ( non-
filterable particles). Turbid waters are unacceptable to consumers.
Turbidity is measured through passing a beam of light through the water sample,
and recording its scattering. The quantity of light scattered is dependent upon the
concentration and size of distribution of particles. Turbidity meter is generally
used for measuring turbidity and its expressed in Nephelometric Turbidity Units
(NTU).
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
UNIT II: WATER SOURCES AND WATER QUALITY

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Water Quality Parameters (Physical)
UNIT II: WATER SOURCES AND WATER QUALITY
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
Turbidity meter

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Water Quality Parameters (Physical)
- Solids: It is the mass of solids present in water. Total Solids (TS) i.e. the mass
present in water could be either in dissolved (Total Dissolved Solids) or
suspended form (Total Suspended Solids). And these solids (TS) could be either
volatile or fixed by nature. The measurements of total solids are carried out using
Gravimetric analysis.
- Turbidity: It is an optical property, describing the clarity or haziness of the water
caused by the presence of very fine suspended or colloidal particles ( non-
filterable particles). Turbid waters are unacceptable to consumers.
Turbidity is measured through passing a beam of light through the water sample,
and recording its scattering. The quantity of light scattered is dependent upon the
concentration and size of distribution of particles. Turbidity meter is generally
used for measuring turbidimeter and its expressed in Nephelometric Turbidity
Units (NTU).
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
UNIT II: WATER SOURCES AND WATER QUALITY

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Water Quality Parameters (Chemical)
- pH (potential of Hydrogen): Measured using pH meters. pH of fresh water ranges
from 6.8 to 8, however it could vary from around 4.5 to over 10 in certain cases.
Note: ( 7 indicates neutral, less than 7 indicates acidic and more than 7 indicates alkaline )
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
pH paper strips
pH meter
UNIT II: WATER SOURCES AND WATER QUALITY

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Water Quality Parameters (Chemical)
- Dissolved Oxygen (DO): It is the amount of oxygen dissolved in water. The water system
may gain oxygen from atmosphere and aquatic plants and lose oxygen from respiration
by aquatic animals and chemical/biochemical reactions.
- DO levels in water fluctuate over 24 hour period and seasonally, and vary with water
temperature and altitude. Cold water holds more oxygen and warm water holds less
oxygen at higher altitudes. It is measured using DO meter.
- Biological/Biochemical Oxygen Demand (BOD): It is a measure of the amount of oxygen
required/consumed by microorganisms to break down organic matter in water under
aerobic condition at a specified temperature (25oC). It is commonly used as an indicator of
the degree of organic pollution in water.
- Measured by monitoring the oxygen levels in a water sample over a period of 5 days,
during which time microorganisms break down the organic matter in the sample,
consuming oxygen in the process. The difference in oxygen level between beginning and
end of test period is used to calculated BOD which is expressed in parts per million or
mg/l
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
UNIT II: WATER SOURCES AND WATER QUALITY

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Water Quality Parameters (Chemical)
- Chemical Oxygen Demand (COD): It is a measure of oxygen required to chemically oxidize
organic matter and inorganic matter in water, under specific conditions, into carbon
dioxide and water. It is expressed in ppm or mg/l.
- COD is useful indicator of the overall quality of water, as high COD are often associated
with pollution and cause oxygen depletion whereby harming the aquatic life.
- COD is always greater than BOD
- Heavy Metals: Heavy metals in small/trace quantities are useful, while when present in
excess becomes toxic and imposes risk to human health and the environment. Metals
such as Arsenic (As), Cadmium (Cd), Chromium (Cr), Mercury (Hg), etc., are classified as
priority elements.
- Nutrients: Nitrogen and Phosphorus are the major nutrients found in water systems.
Algal blooms due to excess of these nutrients are not only an ecological problems, but
may be harmful to humans because of productions of toxins and bacterial growth that can
make people sick upon contact.
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
UNIT II: WATER SOURCES AND WATER QUALITY

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Water Quality Parameters (Chemical)
- Chemical Oxygen Demand (COD): It is a measure of oxygen required to chemically oxidize
organic matter and inorganic matter in water, under specific conditions, into carbon
dioxide and water. It is expressed in ppm or mg/l.
- COD is useful indicator of the overall quality of water, as high COD are often associated
with pollution and cause oxygen depletion whereby harming the aquatic life.
- COD is always greater than BOD
- Heavy Metals: Heavy metals in small/trace quantities are useful, while when present in
excess becomes toxic and imposes risk to human health and the environment. Metals
such as Arsenic (As), Cadmium (Cd), Chromium (Cr), Mercury (Hg), etc., are classified as
priority elements.
- Nutrients: Nitrogen and Phosphorus are the major nutrients found in water systems.
Algal blooms due to excess of these nutrients are not only an ecological problems, but
may be harmful to humans because of productions of toxins and bacterial growth that can
make people sick upon contact.
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
UNIT II: WATER SOURCES AND WATER QUALITY

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Water Quality Parameters (Chemical)
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
Chronic exposure to arsenic leads to cancers of the skin,
liver, and lungs, diabetes, and cardiovascular disease
35 Million people in Bangladesh subjected to arsenic
poisoning
Blue Baby Syndrome due to too
much nitrate (nitrogen ) in water
UNIT II: WATER SOURCES AND WATER QUALITY

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Water Quality Parameters (Chemical)
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
Algal bloom due to eutrophication ( excessive nutrients)
UNIT II: WATER SOURCES AND WATER QUALITY

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Water Quality Parameters (Chemical)
- Water Hardness: Hardness is caused by the presence of Calcium (Ca2+ ) and Magnesium
(Mg2+) ions as bicarbonates - Ca(OH)2 , Mg(OH)2 ; Sulphates - CaSO4, MgSO4 ; Chloride –
CaCl2, MgCl2, etc.
- Bicarbonates of Ca and Mg will lead to temporary hardness, while
sulphates/chlorides/nitrates of Ca and Mg leads to permanent hardness.
- Hard water can cause a variety of problems, such as scaling in pipes and appliances,
reduced effectiveness of soaps and detergents, and a bitter or metallic taste.
UNIT II: WATER QUALITY
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1

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Water Quality Parameters (Chemical)
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
Scale formation due to water hardness
UNIT II: WATER SOURCES AND WATER QUALITY

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Water Quality Parameters (Biological)
- Maximum Probable Number: It is most commonly applied parameter for microbial quality
testing of water. Fecal Coliforms act as an indicator for fecal contamination of water.
- Fecal coliforms are group of bacteria that are commonly found in the feces of humans
and other warm-blooded animals. They are typically harmless to humans, but they can
indicate the presence of other, more harmful bacteria or viruses that can cause illness.
- Thus, it is considered as an important parameter to monitor the levels of fecal coliforms
in water to ensure the safety of drinking water and recreation water activities.
- E.coli (Escherichia Coli) indicates the fecal coliforms in water.
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
UNIT II: WATER SOURCES AND WATER QUALITY

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Water Quality Parameters (Biological)
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
Fecal Coliform (E.Coli)
UNIT II: WATER SOURCES AND WATER QUALITY

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Drinking Water Quality Limits ( Physical & Chemical parameter )
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
S. No Parameter Unit Acceptable Limit Permissible
Limit
Standard Codes
1 Colour Hazen Units 5 50 BDWQS 2016
2 pH ___ 6.5 - 8 6 - 9 BDWQS 2016
3 Turbidity NTU __ 5 BDWQS 2016
4 Total Suspended Solids mg/L 25 100 BDWQS 2016
5 Total Suspended Solids mg/L 500 2000 IS 10500:2012
6 Total Dissolved Solids mg/L 500 2000 IS 10500:2012
7 Alkalinity mg/L as CaCO3 200 600 IS 10500:2012
8 Hardness mg/L as CaCO3 200 600 IS 10500:2012
9 Calcium mg/L as CaCO3 75 200 IS 10500:2012
10 Magnesium mg/L as CaCO3 30 100 IS 10500:2012
11 Dissolved Oxygen mg/L 4 6 BDWQS 2016
UNIT II: WATER SOURCES AND WATER QUALITY

28. MID-TERM REVIEW, 2017
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Drinking Water Quality Limits ( Physical & Chemical parameter )
E n v i r o n m e n t a l E n g i n e e r i n g , E V E 2 0 1
S. No Parameter Unit Acceptable Limit Permissible
Limit
Standard Codes
12 Free Residual Chlorine mg/L 0.2 0.5 BDWQS 2016
13 Iron mg/L 0.3 ___ BDWQS 2016
14 Manganese mg/L 0.4 ___ BDWQS 2016
15 Sulphate mg/L 250 BDWQS 2016
16 Fluoride mg/L ___ 1.5 BDWQS 2016
17 Nitrates mg/L ___ 50 BDWQS 2016
18 Arsenic mg/L 0.01 0.05 BDWQS 2016
19 Lead mg/L 0.02 0.02 BDWQS 2016
20 Mercury mg/L 0.006 ___ BDWQS 2016
21 BOD5 mg/L 2 5 BDWQS 2016
22 COD mg/L 5 WHO
UNIT II: WATER SOURCES AND WATER QUALITY

29. Have a Great day….
PHURBA TAMANG