ENVIS Centre on Hygiene, Sanitation, Sewage Treatment Systems and Technology

As per the latest estimate out of 22,900 Mld of wastewater generated in the country, only about 5900 Mld (26%) is treated before letting out, the rest i.e., 17000 Mld is disposed of untreated. Twenty seven cities have only primary treatment facilities and forty-nine have primary and secondary treatment facilities. The level of treatment  available in cities with existing treatment plant varies from 2.5% to 89% of the sewage generated.
The total wastewater generated by the 299 class I cities is 16,662 Mld approximately 81% of the water supplied. The state of Maharashtra alone contributes about 23%, while Ganga river basin contributes about 31% of the waste generated. Only 74% of the total wastewater generated is collected. Out of 299 class I cities 160 cities have sewerage coverage for more than 75% of the population and 92 cities have between 50 and 75% of population coverage. On the  whole 70% of the population of class I cities are provided with sewerage facility. The type of sewerage system is either open or closed or piped.

Status on Sewage Generation in Metropolitan Cities, Class-I Cities and Class-II Towns:

Discharge of untreated sewage in water courses both surface and ground waters is the most important water polluting source in India. Out of about 38000 million liter per day of sewage generated treatment capacity exists for only about 12000 million liter per day. Thus, there is a large gap between generation and treatment of wastewater in India. Even the treatment capacity existing is also not effectively utilized due to operation and maintenance problem. Operation and maintenance of existing plants and sewage pumping stations is not satisfactory, as nearly 39% plants are not conforming to the general standards prescribed under the Environmental (Protection) Rules for discharge into streams as per the CPCB’s survey report.. In a number of cities, the existing treatment capacity remains underutilized while a lot of sewage is discharged without treatment in the same city. Auxiliary power back-up facility is required at all the intermediate (IPS) & main pumping stations (MPS) of all the STPs.

Status of Municipal Wastewater Generation and treatment capacity of Metropolitan Cities:

• There are 35 metropolitan cities (more than 10 Lac Population), 15,644 Millions Liter Per Day (MLD) of sewage is generated from these metropolitan cities. The treatment capacity exists for 8040 MLD i.e. 51% is treatment capacity is created.

• Among the Metropolitan cities, Delhi has the maximum treatment capacity that is 2330 MLD (30% of the total treatment capacity of metropolitan cities)

• Next to Delhi, Mumbai has the capacity of 2130 MLD, which is 26% of total capacity in metropolitan cities.

• Delhi and Mumbai therefore in combination have 55% of treatment capacity of the metropolitan cities.

• Some cities such as Hyderabad, Vadodara, Chennai and Ludhiana and Ahemedabad treatment capacity meets the volume of generation.

• Cities like Delhi, Dhanbad have more than 50% capacity, rest of the cities have the capacity less than 50%.

Status of sewage generation and treatment capacity in metropolitan cities

Source: Status of sewage in India(CUPS/61/2005-06)- Central Pollution Control Board

State-wise sewage generation of Class-I Cities and Class-II Towns

Source: http://www.cpcb.nic.in/upload/NewItems/NewItem_153_Foreword.pdf

Water supply, wastewater generation, treatment in class I cities (MLD)

Source: http://www.cseindia.org/userfiles/policy_paper_sm.pdf

Water supply, wastewater generation, treatment in class II cities (MLD)

Source: http://www.cseindia.org/userfiles/policy_paper_sm.pdf