Water Quality Standards for different users

S.No.	Designated-Best-Use	Class of	Criteria	Some Examples from Indian
		Water
1	Drinking Water Source without			River
	conventional treatment but after	A	1. Total Coliforms
	disinfection		Organism MPN/IOOml	1. Beas at Manali Himachal
			shall be 50 or less	Pradesh
			2. pH between 6.5 and 8.	2. Ravi at Madhopur, Himachal
			3. Dissolved Oxygen	Pradesh
			6mg/1 or more
			4. Biochemical Oxygen
			Demand 5 days 20OC
			2mg/1 or less
2	Outdoor bathing (Organised)	B	1. Total Coliforms	1. Ganges at Reshikesh, Uttar
			Organism MPN/IOOml	Pradesh
			shall be 500 or less	2. Tapi atNepanagar, Madhya
			2. pH between 6.5 and 8.5	Pradesh
			3. Dissolved Oxygen
			5mg/1 or more
			4. Biochemical Oxygen
			Demand 5 days 20OC
			3mg/1 or less
3	Drinking water source after	C	1. Total Coliforms	1. Achankoli at Thumpaman,
	conventional treatment and		Organism MPN/IOOml	Kerala
	disinfection		shall be 5000 or less	2. Cauvery at Napokulu
			2. pH between 6 to 9	Barrage, Karnataka
			3. Dissolved Oxygen
			4mg/1 or hore
			4. Biochemical Oxygen
			Demand 5 days 20OC
			3mg/1 or less
4	Propagation of Wild life and	D	1. pH between 6.5 to 8.5	1. Brahmani at Panposh, Orissa
	Fisheries		2. Dissolved Oxygen	2. Brahmaputra at Dibrugarh,
			4mg/1 or more	Assam
			3. Free Ammonia (as N)
			1.2 mg/l or less
5	Irrigation, Industrial Cooling,	E	1. pH between 6.0 to 8.5	1. Mahi at the Confluence of
	controlled Waste disposal		2. Electrical Conductivity	River Chap, Gujurat
			at 25OC micro mhos/cm	2. Sabarmati at Miroli Village,
			Max 2250 3. Sodium	Gujurat
			absorption Ratio Max. 26
			4. Boron Max. 2mg/1

Table indicates various limits for a number of water quality parameters that are partly chemical, biological or physical. The Central Pollution Control Board (CPCB) that regulates water quality in India has classified water standards based on five broad categories of use. Drinking water, representing class A should not have more than 50 coliform counts/100 ml. And the biological oxygen demand (BOD), an index of the health of water to support life, should be maximum 2 mg/l. Most of the river waters in India at various locations are generally not suitable for directly drinking with high BOD and at places high coliform counts acting as the critical barriers. Class B represents requirement for bathing can have double the level for coliform counts than in class A but other parameters should be about the same order of magnitude. Most of the rivers at a few selective points such as Rishikesh for the Ganges, Ranganthitu for the Cauvery and Mandhavim in Goa are suitable for bathing. Class C refers to water that has undergone some form of treatment and disinfecting and for this water coliform could go upto 5000 counts/100 ml while the BOD has to be less than 3 mg/l. A number of water bodies such as the Sukhna lake in Chandigarh, Ramgarh Lake in Udaipur, Asthamudi lake in Kerala, Cauvery river at Tiruchirappali and Narmada river at Bharuch come under this categories. Class D represent the water quality requirements for wild life and free ammonia should be less than 1.2 mg/l besides dissolved oxygen >4 mg/l. Many water bodies in Bihar, Orissa, Maharashtra, Gujarat and some locations in river Ganga such as Kanpur and Rajmahal and Pichola lake in Udaipur come under this category. Class E represents irrigation and industrial requirements that should not have Sodium Absorption Ratio (SAR) >26 and conductivity >2250 µS/cm. Some lakes in Pondicherry, Ganga at Varanasi comes under this category. There are still some water bodies at various places throughout the country that are even below class E meaning totally unfit for any use. Examples of such bodies can be found in river Sabarmathi in Ahmedabad, creeks of Elephanta Island in Maharashtra and Ashthamudi backwater in Quilon, Kerala. Though the water quality criteria that have been used by CPCB are very broad keeping in mind the ground reality in India, still there are so many water bodies that are not fit for one or other type of use. Hence we do have a serious problem with water quality and not just quantity alone.

The United States Environmental Protection Agency (US-EPA) has evolved a wide range of water quality parameters that are specific to anthropogenic input to water bodies and limits to be followed before using such water for drinking water purposes. Table-11 summerises various parameters (EPA) that have been identified so far in water and limits set with possible health aspects. Cyanide, selenium and Arsenic are very toxic elements and there are no standard limits in India that can be followed but many industries discharge these components to the water bodies; hence we have to follow some standards and the US-EPA at present has widely acceptable standards for many such parameters. Even among microorganisms the US-EPA has laid out very strict controls for industries and their microbiological limits and turbidity values for drinking water can be summerised as follows:

Giardia lamblia : 99.99% killed or inactivated

Viruses : 99.99% killed or inactivated

Legionella : no limits but by controlling the above bacteria, these bacteria will also be automatically regulated

Turbidity : should not exceed 5 turbidity units of nephelometric units (NTU); any treated water with filters should not have more than 1 NTU

Heterotrophic plate count : not more than 500 bacterial counts/ml.

The dissolved load of river water could be inorganic or organic in origin. Soil mineral reaction gives the water most of the inorganic constituents where as decomposition of plant debris give most of the organic constituents such as the dissolved organic carbon (DOC), dissolved humic acids and many organic compounds. There are also solid particles either as sediments or as debris from soil wash out carried by the river, collectively known as Total Suspended Matter (TSM). These TSM actually are important as storehouse of many nutrients that are required for many biological systems. The Ganges river, for example carry an enormous amount of silt as TSM and this silt is very rich in nutrients such as C, N and P that support many life forms. The total sediment load of the Ganges and Brahmaputra alone is around a billion tonnes per year and most of this goes to the oceans. Other rivers such as the Godavari and Narmada also carry sediments but in much lesser quantity than the Himalayan river systems. The TSM also is useful in regulating the dissolved load of river due to interaction in the river environment and may also, at places control some of the pollutants such as the heavy metals (Hg, As, Cd etc).