124 of 144 samples from rainwater pits in Dwarka CGHS societies contained faecal coliform: Delhi Jal Board

In Dwarka, 124 of 144 rainwater harvesting pits tested positive for faecal coliform, raising concerns over groundwater contamination, says Delhi Jal Board.

New Delhi

The NGT has been hearing the case since February 2023, on a plea by a Dwarka resident alleging rainwater harvesting pits in the subcity were contaminating groundwater. (Representative photo/HT Archive)

Faecal coliform was found in 124 of 144 samples collected from rainwater harvesting pits at cooperative group housing societies (CGHS) in Dwarka in September 2025, the Delhi Jal Board (DJB) told the National Green Tribunal (NGT), adding it asked the Delhi Pollution Control Committee (DPCC) to impose environmental compensation against errant societies.

Previously, the DJB had said this could indicate contamination of the groundwater table by sewage.

The NGT has been hearing the case since February 2023, on a plea by a Dwarka resident alleging rainwater harvesting pits in the subcity were contaminating groundwater. A joint inspection by an NGT-appointed expert committee in May 2023, which included members from the DPCC and the DJB, initially, found that rainwater harvesting (RWH) pits at 180 of 235 societies in Dwarka contained high ammoniacal nitrogen and high total dissolved solids.

A subsequent inspection, as per a report dated March 27, had found 115 societies had faecal coliform, with another four societies not having operational harvesting pits. The DJB, in an affidavit dated October 30, but uploaded on Tuesday, said samples were lifted from 144 societies in September.

“This included 115 societies with prior faecal coliform presence, 4 societies with non-functional RWH systems and 25 societies with dry RWH pits during the previous sampling. The presence of faecal coliform was found in 124 pits; 8 were found to be dry, work was in progress to fix the RWH pits in 7 societies and at 2 societies, it was found non-functional,” said the DJB in its submission, adding three societies also refused to allow samples to be collected.

DJB said it wrote to the DPCC in March over past violations and has sought from the DPCC member secretary an action taken report on the imposition of environmental compensation (EC) on CGHS societies found polluting the groundwater.

“That on the matter regarding disconnection of water connection as per DJB rules, it is being continuously pursued and gradually all societies are being approached – both verbally and in writing to comply as per the quality parameters...” it said.

In a submission on August 21, 2025, the DJB said it has prepared fresh guidelines for setting up RWHs in Delhi, including when calling for RWH pits not to be built around stormwater drains, as it may lead to contamination. “It is to be ensured that no RWH structure comes up in storm water drain areas. Further, a separator is required to be installed to bypass the first rain from entering into the RWH structure to avoid contamination of the groundwater,” said the report, referring to the meeting, where the issue of installation of piezometers – used to measure the increase or decrease in the groundwater table was also raised.