In absolute terms, these cities and towns together are generating an estimate sewage of 38,254 Million Litres Per Day (MLD) as per data available in 2008 while treatment capacity is just 11,787 MLD which shows a capacity gap of 26,467 MLD.
"This evidently indicates ominous position of sewage treatment, which is the main source of pollution of rivers and lakes and hence there is an urgent need for implementing an action plan for arrest of pollution of rivers," the report says.
This is the fourth report in the series which provides the status of water supply, sewage generation and treatment of 498 class I cities (having over one lakh population) and 410 class-II towns.
As per the report, of the total 38,254 MLD sewage, maximum contribution of over 35,000 MLD comes from class I cities while remaining 2,696 MLD is from class-II towns.
Against this, the total sewage treatment capacity of class-I cities (498) is 11,553.68 MLD, which is merely 32 per cent of the sewage generation.
"Out of 11,553.69 MLD sewage treatment capacity, 69 per cent (8,040 MLD) is treated in 35 metropolitan cities, thus indicating that other than metropolitan cities, the capacity of 462 Class-I cities is only 31 per cent," the report says.
Seeking active role from civic agencies, the pollution watchdog has asked them to realise the problem of contaminated water bodies and pay attention to their liability to set up sewage treatment plants (STP) in cities and towns to check it.
The activity requires to be recognised as one of the most important indicators of overall development of the country and a very thoughtful action plan to fill the widening gap between sewage generation and treatment capacity is required, the report says.
For operation and maintenance needs of sewage treatment plants, the environment ministry has already submitted a proposal to the 13th Finance Commission for grant of Rs 1,320 crore as a one-time allocation for the next five years.
"Considering the urgency of preventing pollution of our water bodies and preserving our precious water resources, sewage treatment and re-utilisation of treated sewage need to be accorded higher priority," the report says.
Operation and maintenance of existing plants and sewage pumping stations is also a very neglected field, as most of the treatment plants are not conforming to the general standards for discharge into streams.
Noting that the STPs were usually run by untrained personnel, operational parameters are not regularly analysed and day-to-day variation in performance of most of the STPs is not evaluated, the report stresses on deploying skilled persons having adequate knowledge.