NEW DELHI: The Delhi government is working on a policy for the use of treated sewage water in construction activities and irrigation works as part of efforts to conserve groundwater, officials said on Friday.
Water from sewage treatment plants (STPs) operated by the Delhi Jal Board (DJB) and the Delhi Development Authority (DDA) is already being used extensively for horticulture purposes.Addressing the issue, Delhi Public Works and Water Minister Parvesh Sahib Singh said a policy is being framed by the DJB to ensure that large quantities of treated water from Sewage Treatment Plants are utilised in activities where potable water is unnecessary.
The Jal Board is actively promoting the use of treated effluent, and around 89 million gallons per day (MGD) is currently supplied for non-potable purposes to agencies such as the Central Public Works Department, Delhi Development Authority, New Delhi Municipal Council and Municipal Corporation of Delhi, officials said.
However, with regard to wider use of treated wastewater — especially in government construction works and irrigation of parks—the Delhi government is now considering a comprehensive policy. Officials further said that other applications, including firefighting, may also be explored.
Treated water from Sewage Treatment Plants is likely to be used first in construction activities undertaken by government agencies. Later, the possibility of supplying it to private firms at affordable rates may also be explored, officials said.
Meanwhile, technical aspects related to the use of treated water in construction activities will also have to be examined, as the Bureau of Indian Standards has prescribed guidelines in this regard. Water with a pH level between 6 and 8.5, and total dissolved solids not exceeding 2,000 parts per million, is considered suitable for construction purposes. Officials said poor-quality water can damage iron and concrete and affect construction quality.
In addition, parks maintained by various government agencies and resident welfare associations may be supplied treated water through pipelines connected to STPs. Small decentralised STPs could also be set up near parks to treat local domestic sewage and use it for horticulture purposes.
Meanwhile, a 2024 report by the Central Ground Water Board showed that Delhi is extracting more groundwater than it recharges. Of the 34 assessed tehsils in the national capital, 14 have been identified as “over-exploited”, 13 as “critical”, two as “semi-critical”, and only five as “safe”. Officials said safe reuse of treated water is emerging as a national priority amid increasing pressure on freshwater sources due to population growth.
Currently, Delhi’s STPs generate around 530 MGD of treated water, of which only about 105 MGD is being utilised, mainly for roadside plantations, green areas and lake restoration, officials added.
The Delhi Jal Board has also approved a Rs 90-crore project to transport treated water from sewage treatment plants for horticultural purposes across the national capital.