Faecal coliform found in Dwarka rainwater pits, says Delhi Jal Board in NGT report

A survey of rainwater harvesting pits in Dwarka’s societies found that nearly two-thirds (65.3%) of all samples analysed had traces of faecal coliform in water, according to findings submitted to the National Green Tribunal (NGT) by the Delhi Jal Board (DJB).

Further, RWH pits in four societies were found to be non-functional, while the pit was found dry in 25 societies. This means that only 32 of the 176 samples, or 18% of all sites, did not contain faecal coliform matter.

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DJB officials said directions have been issued to both the revenue department and the DPCC to initiate corrective actions and impose penalties.

The presence of faecal coliform bacteria indicates contamination of a waterway with the faecal material of humans or animals. As per the drinking water standards prescribed in IS 10500:2021, faecal coliform should not be detectable at all in a 100ml sample.

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In its latest report dated March 27, DJB said it collected samples from 176 societies between September and December 2024. “In four societies, the RWH pits were non-functional. In 25 societies, the pit was found dry and in 32 societies, faecal coliform was not found in the water sample,” the DJB said in its submission.

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“The DJB has sent a letter to DPCC for imposing environmental compensation to the defaulters (societies) as per the Environment (Protection) Act, 1986,” the DJB statement mentioned, adding the revenue department has also been asked to submit a report on the actions taken.

To recall, the NGT has been hearing the plea since February 2023 after a Dwarka resident had alleged that rainwater harvesting pits in the region were leading to groundwater contamination. The tribunal then appointed an expert committee comprising members from NGT, DJB, and Delhi Pollution Control Committee (DPCC) and an inspection in May that year found RWH pits in 235 societies in Dwarka. Out of these, pits in 180 societies had high ammonical nitrogen as well as total dissolved solids.

Meanwhile, in May 2024, DPCC had carried out an inspection by themselves, and found faecal coliform in 103 societies, an indication that sewage was mixing with rainwater, or directly entering these pits, eventually leading to groundwater contamination in Dwarka, DPCC officials informed.

The Delhi government had made rainwater harvesting (RWH) systems mandatory in 2012 and as per law, non-compliance can attract a penalty of 1.5 times the amount of water bill. A 10% rebate is given on the water bill if an RWH system is installed. It is also mandatory for government buildings in Delhi to have RWH, however, maintenance of these structures has long been a problem.

The DJB In March last year also issued an order, asking water consumers to ensure the run-off of waste water from balconies and parking spaces does not contaminate the groundwater through rainwater harvesting pits, stating failure to do so may lead to withdrawal of the rebate provided to users.