Staff Reporter
Panaji
The Ministry of Jal Shakti has issued advisories to all state and Union territory administrations regarding the prevention of potential groundwater contamination due to rainwater harvesting (RWH) systems in urban areas.
The move comes after the National Green Tribunal said that RWH systems could be a source of groundwater contamination if not implemented properly.
The NGT had directed the ministry to look into the issue urgently through a joint committee with the Central Pollution Control Board (CPCB) and the Ministry of Urban Development. A committee was subsequently formed which visited selected RWH sites in Delhi, Haryana, Karnataka, Rajasthan, and Tamil Nadu.
Key findings of the committee include deficiencies in RWH implementation at certain places, with lack of attention to preventing contaminants from breaching the systems and eventually reaching groundwater reserves, especially where harvested water is used for artificial recharge.
Goa has amended its existing policy on Rainwater Harvesting (Amendment) 2022 but it doesn’t mention the dos and don’ts on installation of system. But response was not positive.
The committee stressed adhering to the Bureau of Indian Standards Code IS 15797:2008 on implementation of rooftop RWH systems, which provides comprehensive guidelines.
It recommended avoiding RWH for artificial recharge in congested urban areas near sewage systems/landfills where contamination risks are high. Other major recommendations include promoting cluster-based RWH instead of individual household schemes in areas with small households, installing piezometers at large RWH sites for periodic monitoring, designing systems to bypass the first roof flush and prevent mixing with drain/road runoff, and using harvested water strictly for non-potable purposes unless treated.
The committee also suggested promoting concepts like Bengaluru’s RWH Theme Park for public guidance, geotagging all RWH sites for better monitoring visibility, preventing misuse of recharge tube wells for pumping, considering online filters to remove minor contaminants, strengthening District Jal Shakti Kendras and raising public awareness. Monthly random inspections by district administrations and corrective action were also recommended. The ministry has issued detailed dos and don’ts for planning, construction, maintenance and monitoring of RWH systems to safeguard groundwater quality.
The dos include choosing the right recharge technique, locating RWH sites at safe distances from contamination sources, providing filters and bypasses for first flush, using dual pipe systems for non-potable use of harvested water, installing piezometers at large-scale RWH sites, and geo-tagging all locations.
Don’ts include avoiding recharge in shallow groundwater areas or near contamination sources like sewage systems, not allowing mixing of drain/road runoff, not locating near landfills/sewage systems, not recharging contaminated water, not diverting domestic wastewater to recharge pits, and not constructing recharge wells beyond the water level.
States have been advised to strictly follow these guidelines and approach CGWB regional offices for technical support if needed.
With rapid urbanisation, rainwater harvesting is crucial for groundwater recharge. However, the NGT’s observations and the committee’s findings highlight the need for stringent implementation to prevent systems from becoming potential contamination sources, defeating their purpose. The advisories aim to facilitate sustainability and safety of urban RWH initiatives across India.