Water pollution and groundwater exploitation are major problems all over India, especially in urban areas. While respective State governments have implemented various schemes to tackle the issues, not all of them are successful. One exception is the programme launched by the government of Karnataka in March 2018—Koramangala-Challaghatta (KC) Valley project. The project is meant to treat 440 million litres of sewage water per day and use that to recharge groundwater in the drought-prone districts of Kolar and Chikkaballapur. It has contributed to making Bengaluru the second largest city in the world, after Mexico city, in terms of the quantity of treated wastewater. The city treats 1,200 million litres of sewage water every day. Another success story in this regard is the case of the east Kolkata wetlands, which are irrigated by untreated wastewater from the city.
A recent assessment by the Indian Institute of Science (IISc), Bengaluru, has documented the results of the KC Valley project. Headed by L.N. Rao from the Centre for Sustainable Technologies (CST), IISc, the study was published on June 15. Pointing out that the project provides a “sustainable solution for freshwater security and wastewater management,” the study records its four major positive outcomes: Ten times improvement in daily groundwater recharge rates; increase in groundwater levels by 58-73 per cent; improvement in groundwater quality; and improvement in agricultural productivity.
“The primary motivation (of the KC Valley project) was to provide a long-term solution to the drought-prone areas of Kolar and Chikkaballapur,” said Krishna Byre Gowda, Revenue Minister of Karnataka, who had steered the project during his term as Minister of Rural Development and Panchayati Raj from 2018 to 2019. Although these areas had experienced an almost unbroken spell of drought from the late 1990s to about 2017, they “had a traditional system of tanks which replenished groundwater and maintained the water table balance throughout the year,” Gowda pointed out. These tanks had dried up due to lack of rains. “So we decided to make an external intervention by utilising Bengaluru’s wastewater,” Gowda said.
Previously, the CST team had conducted a socio-economic assessment of the project where they found that the treated water fulfils three important criteria outlined by the Central Pollution Control Board for the designated best uses of water: improved bathing water quality, wildlife propagation and fisheries management, and irrigation. They observed increased crop productivity across vegetables, fruits, plantations and flowers and an enhancement of livestock rearing and associated milk production activities. The study also noted increases in land value, incomes and employment opportunities.
Vishwanath Srikantaiah, a water conservation expert who has been closely following the KC Valley project, said that the project has “great potential”, and studies like the one by IISc will help improve it further by providing better understanding.
- The Koramangala-Challaghatta (KC) Valley project is meant to treat 440 million litres of sewage water per day and use it to recharge groundwater in the drought-prone districts of Kolar and Chikkaballapur.
- According to an assessment study by the Indian Institute of Science (IISc), Bengaluru, the project has shown positive results.
- The KC Valley project is an example in tackling water crisis in drought-prone areas by using treated wastewater
Elaborating on the problems faced by Kolar prior to the implementation of the project, Rao said, “Excessive utilisation of groundwater resources and surface water in tanks for agricultural irrigation, which is the primary occupation of the district, coupled with a diminishing rainfall pattern [attributable to the district’s semi-arid location] and prolonged periods of moderate to severe droughts, resulted in the depletion of surface water sources and a rapid decline in groundwater levels in the district.” He added that to cope with the depletion of groundwater, borewells had been dug to the depths of 2,000-2,500 feet. The absence of perennial rivers in the district made groundwater recharge a challenging task. The water had also turned salty owing to prolonged periods of drought.
“The Karnataka government has initiated more such projects including Phase II of KC Valley and others like the Hebbal-Nagawara Valley Project, which aims to reuse about 865 million litres of treated wastewater per day for groundwater recharge.”
It is to address these problems that Karnataka’s Minor Irrigation Department and Bangalore Water Supply and Sewerage Board (BWSSB) conceptualised the KC Valley project in 2018. The aim was to recycle Bengaluru’s wastewater at sewage treatment plants in KC Valley and Bellandur, and use the treated water to fill up the lakes that had dried up over the years in Kolar and Chikkaballapur. IISc was engaged to conduct environmental assessments of the project and detect potential problems. It gave the project technological support to improve the functioning of sewage treatment plants, in addition to providing continuous monitoring and evaluation. “As the indirect groundwater recharge using recycled water is the main aim of the project, continuous monitoring of water quality is very important. This is taken care of by IISc,” explained Kavita Verma, lead author of the study and a research scientist at IISc.
In 2018, a Public Interest Litigation was filed against the KC Valley project alleging that the treated water was actually contaminated and had heavy metal content. But the Supreme Court overruled the objection, allowing the State to pump secondary treated water from Bengaluru to the tanks in Kolar. Talking of the case, Srikantaiah said, “It served a positive purpose by bringing discipline to the treatment process and setting up protocols for checking the water for quality before pumping it.”
The project treats wastewater up to the secondary level and then pumps it to 137 tanks that are specifically identified for groundwater recharge. Primary treatment refers to the removal of floating particles like plastics and paper; secondary treatment entails the removal of dissolved organic matter by using bacteria; and tertiary treatment involves making the water fit for drinking. Additional filtration also takes place naturally in the tanks. At Kolar, the sandy and loamy soil further treats the wastewater, as do soil bacteria.
Thus the KC Valley project shows a way forward in tackling water crisis in drought-prone areas by using treated wastewater to recharge groundwater levels. The Karnataka government has initiated more such projects including Phase II of KC Valley and others like the Hebbal-Nagawara Valley Project, which aims to reuse about 865 million litres of treated wastewater per day for groundwater recharge.
However, Rao suggested two areas of improvement: ensuring better quality of water in the surface tanks by avoiding the intervention of local untreated wastewater, and reusing treated wastewater coming from Bengaluru in higher volume to rejuvenate dried-up tanks.
Another way to improve the KC Valley project, according to Srikantaiah, is to incorporate learnings from Jala Samvardhane Yojana Sangha, a tank rehabilitation project undertaken by the Ministry of Water Resources, Government of Karnataka, in 2008. This project organised farmers and others into tank user groups and created an institutional structure for the management of tanks to ensure that groundwater recharge benefits are shared equitably.
Rishika Pardikar is a wildlife and climate change reporter based in Bengaluru.