The Delhi Jal Board (DJB) has issued fresh guidelines for rainwater harvesting (RWH) in the capital city. The new pits should not be built near stormwater drains to prevent underground water contamination, according to the new guidelines.
In an affidavit submitted to the National Green Tribunal (NGT), DJB said that a joint expert committee met on July 31 to examine contamination risks linked to rainwater harvesting structures. The panel recommended installation of groundwater tanks away from stormwater drains. The panel also recommended that separators be installed to divert the first flush of rainwater from entering and contaminating aquifers.
The National Tribunal has been hearing this case since February 2023 after a Dwarka resident alleged that rainwater harvesting pits in the region were polluting the groundwater. After this, a joint inspection involving the Delhi Jal Board and the Delhi Pollution Control Committee (DPCC) officials found that out of 235 societies in Dwarka, 180 had high ammonia, nitrogen, and dissolved solids. Another follow-up inspection in March 2024 reported failure in 115 societies, while four societies had non-functional pits.
Following this series of inspections, the latest submission on 21st August by the Delhi Jal Board said that the 31st July committee has decided to focus on upcoming pits to prevent further contamination.
“It is to be ensured that no RWH structure comes up in stormwater drain areas. Further, a separator is required to bypass the rain from entering into the RWH structures,” the report stated.
Other than this, the committee discussed the use of piezometers (devices that track groundwater level), one in every 5 km. Alongside, it was also noted that the Delhi Jal Board has already set up 95 such devices near sewage treatment plants to monitor the discharge.