With Delhi facing a summer water supply deficit of approximately 250 million gallons per day (MGD), the Delhi Jal Board (DJB) is exploring advanced treatment technologies to convert contaminated groundwater into potable water. The initiative aims to tap aquifers in areas along the Najafgarh drain, Garhi Mandu and other locations where total dissolved solids (TDS), heavy metals and other contaminants occur at high concentrations.
The DJB has issued an expression of interest (EoI) inviting technology providers and research institutions to install and operate treatment systems capable of removing dissolved salts, heavy metals and other pollutants from groundwater extracted through tubewells.
Groundwater Quality and Treatment Standards
According to a project report dated October 16, groundwater in several parts of Delhi contains elevated levels of TDS, fluoride, nitrate, iron, manganese and heavy metals, including arsenic, lead and mercury. These contaminants can make the water unsuitable for direct human consumption without appropriate treatment.
TDS concentrations in the identified areas generally range between 1,500 and 3,000 milligrams per litre, exceeding 10,000 mg/l in some locations.
The DJB has stipulated that the proposed technology must be capable of treating groundwater with TDS levels of 10,000 mg/l or higher and producing drinking water that complies with World Health Organization (WHO) guidelines and Bureau of Indian Standards (BIS) requirements.
Plan to Supplement Delhi’s Water Supply
The initiative forms part of the DJB’s broader plan to install 300–400 tubewells across Delhi to supplement the city’s existing water supply. Officials have identified 26 tubewells near the Najafgarh drain, where groundwater assessments have revealed high TDS concentrations.
The board proposes to establish treatment units on approximately 20,000 square metres of vacant land at the Ujwa underground reservoir (UGR). Treated groundwater could then be blended with the reservoir’s existing water supply of 1.40 million gallons per day.
The project is intended to expand the city’s usable water resources by treating groundwater that would otherwise remain unsuitable for direct consumption.
Proposed Treatment Technologies
The DJB has invited proposals for treatment capacities ranging from 10 MGD to 50 MGD or more. Modular systems that can be expanded according to future requirements are also being considered.
Suggested technologies include high-recovery reverse osmosis and nanofiltration. However, technology providers may propose other proven solutions or combinations of treatment processes that meet the prescribed water quality standards.
In addition to removing dissolved salts and heavy metals, the systems must minimise water wastage, maximise water recovery and provide a plan for managing concentrated reject water generated during treatment.
The proposed initiative could help Delhi make better use of its groundwater resources and ease pressure on the city’s existing water supply systems, provided the treatment technologies can meet drinking water standards reliably and manage treatment waste safely.
