How big is the Problem?

Together, India’s largest cities generate more than 38,254 million litres of sewage each day. Of this, it is estimated that less than 20-30% per cent of what is collected undergoes treatment before it is disposed into freshwater bodies or the sea. Worryingly, these figures exclude sewage generated in informal settlements and in smaller cities and towns where an acute lack of Municipal infrastructure for water supply and sewage collection makes data hard to find. Source: Central Pollution Control Board (CPCB)

Although ~30% sewage is treated, but it is also important to note that treatment from a lot of facilities is substandard and the treated water is still not fit to mix into fresh water sources.

As per Central Pollution Control Board (CPCB) rules, a city or town’s municipality or water authority is responsible for collecting and treating 100 percent of the sewage generated within its jurisdiction. The level to which the sewage has to be treated depends on where it will be disposed—treatment standards are higher for disposal into freshwater bodies than the sea.

Is setting up a STP enough?

Typically even where sewage treatment plants (STPs) exist, the underground sewage collection

network is inadequate so only a small portion goes for treatment. The rest flows into nallahs and drains from where it is pumped into surface water bodies. Sometimes wastewater stagnates in pools from where it leaches into the groundwater table and contaminates underground aquifers.

The fact that the required infrastructure is not able to keep pace with the growth in population and city sprawl has been the biggest reason due to all water related problems in the country. The per capita water demand has growing consistently in the urban areas. More and more water from nearby water sources is been pumped into the city due to which several rivers and lakes dry up way before the onset of the monsoon season.

Wastes from all kind of sources like residential, industry, etc are mixed in water bodies. Due to the absence of treatment facilities these water bodies get polluted and no longer remain fit for human use. A significant percentage of people have no other option but to use this polluted water and as a result contract various water borne diseases.

Over exploitation of the available water resources makes the river beds to dry up and the ground-water table to go down. Drying up of groundwater sources causes huge water scarcity in urban areas. At the same time people in rural areas have to walk even greater distances in search of potable water.

What is the government doing about it?

Centralized Treatement

In order to solve the problem of wastewater in urban areas, a centralized approach for treating waste water has been adopted by the Government. Sewerage lines are been laid throughout the cities to collect wastewater and channel it to a single location where the entire sewage is treated.

Laying sewerage lines to establish a centralized wastewater treatment plant is the first and the most important thing to be established in an urban area. Settlements towards the older parts of the city had been established long ago without the proper planning of civic amenities like Sewage Treatment Plant. In such a case, the only solution is to collect the sewage through underground pipelines and treat it at a different location. However there are various shortcomings of a centralized approach:

Centralized approach needs STPs to be setup with the capacity of treating the entire city’s wastewater. Huge capital cost is incurred in this to the Government. (to the tune of 100 Crores and above)

The cost of laying sewerage lines is far more than setting up of an STP.  At an average, the cost of laying supplementary infrastructure is 2-4 times of that of setting up a centralized STP. A lot of pumping stations have to be setup at regular intervals to facilitate centralized collection.

The wastewater collected centrally belongs to a variety of sources including non-residential sources as well. The treatment is often improper due to the diversity of pollutants.

Since the treatment facility is generally outside the city, therefore reusing of treated water is not possible in a centralized approach nor can the groundwater throughout the city be recharged with this. All the treated water would be discharged in a single location.

The cities are ever expanding and it is impossible for the city administration to lay sewerage lines in the peri-urban areas of the city.

Per Capita Network & Treatment Cost for Sewage

What is the missing part in solving the problem?

Decentralized Treatment

For a complete solution to the wastewater related problems of the city, a combination of a decentralized approach and a centralized approach is required. An only centralized approach or an only decentralized approach would not be able to solve the problem entirely. A balanced approach between the two strategies is required.

Decentralized Sewage Treatment Plants and Effluent Treatment Plants have to be setup throughout the city bounds and in peri-urban areas to tackle the problem effectively. Several merits of a decentralized approach are as follows:-

Setting up of smaller STPs is easier due to the lower capital cost required.

It sounds fair that whoever is generating the waste should be the one to clean it.

Appropriate technologies can be implemented based on whether the wastewater is from a residential or an industrial source.

Application of green technologies is possible in decentralized plants which significantly reduce electricity consumption for treatment. Green technologies STPs can also be integrated beautifully with the surrounding landscape.

Minimum cost of sewerage lines is incurred in decentralized plants. No pumping stations are required in a decentralized approach.

Treated water can be reused at the site for gardening, flushing, car wash, cleaning, etc. This can reduce the overall daily freshwater supply by around 50%.

The treated water can be discharged in nearby water bodies thereby reducing water demand on them and making them perennial. These water sources would not get polluted and the water would remain fit for human use.

The unused treated water can always be used to recharge the groundwater.

Several studies have shown that cost of procuring treated water is about 1/4th of the cost of fresh water supplied from the municipalities.

The biggest and the most important thing for the government is that it makes complete economic sense as well. The cost of making fresh water available to people’s doorsteps is 4 times more expensive than providing treated water.


The cost for treated wastewater in Beijing is 1/4th of the cost of fresh tap water.

Several initiatives that can be taken by the Government

In order to setup an extensive network of decentralized STPs, a multipronged approach is required.

The Central Pollution Control Board has already brought in strict guidelines for effluent discharge. Setting up of STPs has been made compulsory for every major polluter within and outside the city bounds. But, due to various reasons PCB is not able to ensure that these STPs are operated on a regular basis. Setting up a STP and not using it is not going to solve any problem. It has to be ensured that not only people operate the STPs but also reuse the treated water.

The followings things should also be done by the Government to promote decentralized waste water treatment:

4 Responses

Leave a Reply

Your email address will not be published. Required fields are marked *