Soil & Water Conservation Engg.

Lesson 30 Water Quality

30.1 Importance of Water Quality

A wide range of human and natural processes affect the biological, chemical and physical characteristics of water and thus impact water quality. It includes contamination by pathogenic organisms, trace metals, toxic chemicals, introduction of non-native species etc. Changes in the acidity, temperature and salinity of water harm aquatic ecosystems and make water unsuitable for human use. Numerous human activities which include agriculture, industry, mining, disposal of human waste, population growth, urbanization, climate change etc impact water quality. Water contamination weakens or destroys natural ecosystems that support human health, food production, and biodiversity.

Poor water quality threatens the health of people and ecosystems, reduces the availability of safe water for drinking and other uses and limits economic productivity and development opportunities. There is an urgent need for protecting and improving the quality of water. It can be achieved by preventing future water pollution, treating waters that are already contaminated and restoring the quality and health of rivers, lakes, aquifers, wetlands and estuaries.

In India, agencies like the Indian council of Medical Research (ICMR), Bureau of Indian Standards and Ministry of Works and Housing have formulated certain drinking water standards which are being followed by different authorities. World Health Organization (WHO) has also laid down drinking water standards which are considered as international standards.

30.2 Standards of Water Quality for Different Uses

For any water body to function adequately in satisfying the desired use, it must have the corresponding degree of purity. Drinking water should be of the highest purity. As the magnitude of demand for water is fast approaching the available supply, the concept of management of the quality of water is becoming as important as its quantity. Each water use has specific quality need. Therefore, to set the standard for the desired quality of a water body, it is essential to identify the uses of water in that water body.

• Drinking Water Standards

• Irrigation Water Standards

• Stream Water Standards

• Drinking Water Standards: Drinking water is the water intended for human consumption for drinking and cooking purposes from any source. It includes water supplied by pipes or any other means for human consumption by any supplier.

• Irrigation Water Standards: For the quality of water for irrigation the major parameters of concern are salinity denoted by dissolved solids and conductivity, potentially toxic trace elements, and herbicides. In addition, the presence of sodium is also an important parameter excess quantities of which can deteriorate the soils. High value of sodium may also damage the sensitive crops because of sodium phyto-toxicity. The sodium in waters can be denoted by percent sodium and "sodium absorption ratio" (SAR).

• Stream Standards: Water quality objectives for freshwaters take into account several major uses of water like irrigation, drinking, industry, power generation, recreation etc. All water bodies or stretches are not necessarily required to meet all potential uses. This has led to the concept of classification and zoning of water bodies which indicate that their quality has to meet the requirement of one or more potential uses. For each typical use, water quality criterion should take into account the special constraints on water quality imposed by that use. Based on this, any water body or its stretch can be designated for some particular best use which can be termed as the designated best use. The water resources can be classified or zoned depending upon the designated best use of the water.

In India, the Central Pollution Control Board (CPCB) has developed a concept of designated best use of water. According to this, out of the several uses of water of a particular body, the use which demands the highest quality is termed its designated best use. Five designated best uses have been identified. This classification helps the water quality managers and planners to set water quality targets and design suitable restoration programs for various water bodies (Table 30.1).

Table 30.1. Designated Best Uses of Water (Source IS 2296:1992)

Designated best use	Class	Criteria
Drinking Water Source without conventional treatment but after disinfection	A	1.Total Coliforms Organism MPN/100 ml shall be 50 or less 2. pH between 6.5 and 8.5 3. Dissolved Oxygen 6 mg/l or more 4. Biochemical Oxygen Demand (5 days) at 20 °C, 2 mg/l or less
Outdoor bathing (Organised)	B	1.Total Coliforms Organism MPN/100 ml shall be 500 or less 2. pH between 6.5 and 8.5 3. Dissolved Oxygen 5 mg/l or more 4. Biochemical Oxygen Demand (5 days) at 20 °C, 3 mg/l or less
Drinking water source after conventional treatment anddisinfection	C	1. Total Coliforms Organism MPN/100 ml shall be 5000 or less 2. pH between 6 and 9 3. Dissolved Oxygen 4 mg/l or more 4. Biochemical Oxygen Demand (5 days) at 20 °C, 3 mg/l or less
Propagation of Wild life and Fisheries	D	1. pH between 6.5 and 8.5 2. Dissolved Oxygen 4 mg/l or more 3. Free Ammonia (as N) 4. Biochemical Oxygen Demand (5 days) at 20 °C, 2 mg/l or less
Irrigation, Industrial Cooling, Controlled Waste disposal	E	1. pH between 6.0 and 8.5 2. Maximum electrical conductivity at 25 °C should be 2250 micro mhos/cm 3. Sodium absorption Ratio Max. 26 4. Boron Max. 2 mg/l

 

In India, CPCB has identified water quality requirements in terms of a few chemical characteristics, known as primary water quality criteria. Further, Bureau of Indian Standards has also recommended water quality parameters for different uses in the standard- IS 2296:1992 (Table 30.2).

Table 30.2. Water Quality Standards in India. (Source: IS 2296:1992)

Characteristics	Designated best use
	A	B	C	D	E
Dissolved Oxygen (DO) mg/l, min	6	5	4	4	-
Biochemical Oxygen demand (BOD) mg/l, max	2	3	3	-	-
Total coliform organisms MPN/100 ml, max	50	500	5,000	-	-
pH value	6.5-8.5	6.5-8.5	6.0-9.0	6.5-8.5	6.0-8.5
Colour, Hazen units, max.	10	300	300	-	-
Odour	Un-objectionable			-	-
Taste	Tasteless	-	-	-	-
Total dissolved solids, mg/l, max.	500	-	1,500	-	2,100
Total hardness (as CaCO3), mg/l, max.	200	-	-	-	-
Calcium hardness (as CaCO3), mg/l, max.	200	-	-	-	-
Magnesium hardness (as CaCO3), mg/l, max.	200	-	-	-	-
Copper (as Cu), mg/l, max.	1.5	-	1.5	-	-
Iron (as Fe), mg/l, max.	0.3	-	0.5	-	-
Manganese (as Mn), mg/l, max.	0.5	-	-	-	-
Cholorides (as Cu), mg/l, max.	250	-	600	-	600
Sulphates (as SO4), mg/l, max.	400	-	400	-	1,000
Nitrates (as NO3), mg/l, max.	20	-	50	-	-
Fluorides (as F), mg/l, max.	1.5	1.5	1.5	-	-
Phenolic compounds (as C2H5OH), mg/l, max.	0.002	0.005	0.005	-	-
Mercury (as Hg), mg/l, max.	0.001	-	-	-	-
Cadmium (as Cd), mg/l, max.	0.01	-	0.01	-	-
Salenium (as Se), mg/l, max.	0.01	-	0.05	-	-
Arsenic (as As), mg/l, max.	0.05	0.2	0.2	-	-
Cyanide (as Pb), mg/l, max.	0.05	0.05	0.05	-	-
Lead (as Pb), mg/l, max.	0.1	-	0.1	-	-
Zinc (as Zn), mg/l, max.	15	-	15	-	-
Chromium (as Cr6+), mg/l, max.	0.05	-	0.05	-	-
Anionic detergents (as MBAS), mg/l, max.	0.2	1	1	-	-
Barium (as Ba), mg/l, max.	1	-	-	-	-
Free Ammonia (as N), mg/l, max	-	-	-	1.2	-
Electrical conductivity, micromhos/cm, max	-	-	-	-	2,250
Sodium absorption ratio, max	-	-	-	-	26
Boron, mg/l, max	-	-	-	-	2

30.3National Water Quality Monitoring Programme

Effective monitoring of water quality can influence containment of pollution through better understanding of the problem and devising appropriate solutions for better management. In India, water quality monitoring is being carried out historically for a number of reasons. Following different organizations have been and are currently operating to satisfy their own particular objectives:

• Central & State Pollution Control Boards (CPCB, SPCBs)

• Central Water Commission & State Surface Water departments (CWC, SSWD)

• Central Ground Water Board & State Ground Water Departments (CGWB, SGWD)

• National River Conservation Directorate (NRCD)

• Research Institutions e.g. National Environmental Engineering Research Institute, Nagpur  (NEERI)

• Others Academic Institutions, State Public Health and Environmental

Departments (PHED), Water Supply and Sewerage Boards (WSSB).

Objectives: The preamble of Water (prevention and control of pollution) Act, 1974 stated that pollution control board, both at States and Central levels, are meant to restore and maintain the wholesomeness of water bodies in India. Water quality monitoring is therefore an imperative prerequisite in order to assess the extent of maintenance and restoration of water bodies. The water quality monitoring is performed with following main objectives:

• Rational planning of pollution control strategies and their prioritization,

• To assess the nature and extent of pollution control needed in different water bodies or their part,

• To evaluate the effectiveness of pollution control measures already in existence,

• To evaluate the water quality trend over a period of time,

• To assess the assimilative capacity of a water body thereby reducing cost on pollution control,

• To understand the environmental fate of different pollutants and

• To assess the fitness of water for different uses.

Monitoring Network: The Central Pollution Control Board (CPCB) has established a network of monitoring stations on rivers across the country (Table 30.3). The present network comprises 1700 stations in 27 States and 6 Union Territories spread over the country. The monitoring network covers 353 Rivers, 107 Lakes, 9 Tanks, 44 Ponds, 15 Creeks/Seawater, 14 Canals, 18 Drains and 490 Wells. Among the 1700 stations, 980 are on rivers, 117 on lakes, 18 on drains, 27 on canals, 9 on tank, 15 on creeks/seawater, 44 on pond and 490 are groundwater stations. Presently the inland water quality-monitoring network is operated under a three-tier programme i.e. Global Environmental Monitoring System (GEMS), Monitoring of Indian National Aquatic Resources System (MINARS), and Yamuna Action Plan (YAP). Water samples are being analyzed for 28 parameters consisting of physico-chemical and bacteriological parameters for ambient water samples apart from the field observations. Besides this, 9 trace metals and 28 pesticides from selected samples are analyzed. Bio monitoring is also carried out on specific locations. In view of limited resources, limited numbers of organic pollution related parameters are chosen for frequent monitoring i.e. monthly or quarterly and major cations, anions, other inorganic ions and micro pollutants (Toxic Metals & POP’s) are analyzed once in a year to keep a track of water quality over a long period of time. The water quality data are reported in Water Quality Status Year Book.

Table 30.3. Statewise Water Quality Monitoring Stations. (River, Lake, Tank, Pond, Canal, Creek/Sea water, Drain and Well)

State	Total No.
Andhra Pradesh	96
Assam	101
Bihar	86
Chandigarh	11
Chhattisgarh	27
Daman, Diu, Dadra And Nagar Haveli	24
Delhi	15
Goa	29
Gujarat	113
Haryana	23
Himachal Pradesh	104
Jammu & Kashmir	9
Jharkhand	36
Karnataka	45
Kerala	110
Lakshadweep	16
Madhya Pradesh	105
Maharashtra	196
Manipur	20
Meghalaya	13
Mizoram	6
Nagaland	8
Orissa	93
Pondicherry	22
Punjab	43
Rajasthan	51
Sikkim	14
Tamil Nadu	32
Tripura	13
Uttar Pradesh	111
Uttaranchal	29
West Bengal	99
Total	1700

Parameters Observed: The water samples are analysed for 9 core parameters and 19 general parameters. The monitoring agencies also analyze the trace metals at few locations. The list of parameters being identified under the National Water Quality Monitoring Programme is presented in Table 30.4.

Table 30.4. List of parameters monitored under National Water Quality Monitoring Programme

Core Parameters (9)	Field Observations (7)
PH	Weather
Temperature	Depth of main stream/depth of water table
Conductivity, μmhos/cm	Colour and intensity
Dissolved Oxygen, mg/l	Odour
BOD, mg/l	Visible effluent discharge
Nitrate – N , mg/l	Human activities around station
Nitrite – N, mg/l	Station detail
Faecal Coliform, MPN/100 ml	Trace Metals (9)
Total Coliform, MPN/100 ml	Arsenic, μg/l
General Parameters (19)	Cadmium, μg/l
Turbidity, NTU	Copper, μg/l
Phenolphthalein Alkalinity,CaCO3	Lead, μg/l
Total Alkalinity, as CaCO3	Chromium (Total) , μg/l
Chlorides, mg/l	Nickel, μg/l
COD, mg/l	Zinc, μg/l
Total Kjeldahl - N, as N mg/l	Mercury, μg/l
Ammonia - N, as N mg/l	Iron (Total) , μg/l
Hardness, as CaCO3	Pesticides (15)
Calcium, as CaCO3	Alpha BHC, μg/l
Sulphate, mg/l	Beta BHC, μg/l
Sodium, mg/l	Gama BHC (Lindane) , μg/l
Total Dissolved Solids, mg/l	O P DDT, μg/l
Total Fixed Dissolved Solids, mg/l	P P DDT, μg/l
Total suspended Solid, mg/l	Alpha Endosulphan, μg/l
Phosphate, mg/l	Beta Endosulphan, μg/l
Boron, mg/l	Aldrin, μg/l
Magnesium, as CaCO3	Dieldrin, μg/l
Potassium, mg/l	Carboryl(Carbamate) , μg/l
Fluoride, mg/l	2-4 D, μg/l
Bio-Monitoring (3)	Malathian, μg/l
Saprobity Index	Methyl Parathian, μg/l
Diversity Index	Anilophos, μg/l
P/R Ratio	Chloropyriphos, μg/l

Frequency of Monitoring: Out of the total monitoring stations of 1700, 32% stations monitor on monthly basis, 28.82 % on half yearly basis and 38.64% on a quarterly basis.

River Basin Wise Distribution of Water Quality Monitoring Stations: The numbers fresh water quality monitoring stations on each river (Table 30.5), its tributary, sub tributary, lake, ponds, tanks, canals, creeks and on groundwater reveal that:

• 764 stations i.e. 44.94% are located in major River basins. Out of them river Ganga dominates with nearly 30.49% of the stations of major river basin.

• Medium rivers have 216 stations i.e. 12.70% of the total stations, whereas; 107 lakes, 9 tanks and 44 ponds have 170 stations which are nearly 10% of the total stations.

• Creeks, canals, and drains have only 60 stations.

• Next to major river basin, the major numbers of monitoring stations are for  ground water and with a number of 490 stations accounts for 28.82% of the total stations.

Table 30.5. River Basinwise Distribution of Water Quality Monitoring Stations (2009)

River (main stream)	Total stations
Baitarani (5)	6
Brahmani (16)	25
Brahmaputra (10)	68
Cauvery (20)	36
Ganga (52)	233
Godavari (35)	83
Indus	72
Krishna (22)	93
Mahi (9)	15
Mahanadi (22)	48
Narmada (21)	25
Pennar (5)	5
Sabarmati (9)	12
Subarnarekha (12)	13
Tapi (14)	30
Medium rivers	216
Lakes (117)	170
Tanks (9)
Ponds (44)
Creeks, Canals and Drains	60
Groundwater	490
Total	1700

Keywords: Designated best uses of water; Monitoring network; National water quality monitoring programme

Reference

IS 2296:1992: http://www.nih.ernet.in/rbis/india_information/water%20quality%20standards.htm

National Water Quality Monitoring Programme:

http://www.cpcb.nic.in/divisionsofheadoffice/pams/NWMP.pdf

Suggested Readings

Merritt, L. B. 1977. Water Quality: An Introduction. The American Biology Teacher, 313-315.

Tebbutt, T. H. Y. 1997. Principles of water quality control. Butterworth-Heinemann.