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By Apoorva Bamal and Niyati Seth

With a population of nearly 19 million, the National Capital Territory of Delhi is one of the most rapidly growing urban centers in the world. Urban and regional demand for freshwater in Delhi has grown significantly over the last few decades. According to the National Capital Region Planning Board (NCRPB), Delhi uses an average of 1,140 Million Gallons per Day (MGD) drawn from various sources including the rivers Ganga and Yamuna, the Bhakra Storage, and groundwater. Groundwater is crucial as it is extracted through tube and ranney wells for piped water supply in many areas. Additionally, groundwater is also used for agriculture purposes in the outer areas of the region. According to the Central Ground Water Development Board (CGWB, 2011), the average level of exploitation of groundwater in Delhi is 137% which means the annual groundwater consumption is more than the annual extractable groundwater resources. In addition, while Delhi’s population raises demand of 1,140 MGD, the available supply is 937 MGD (Water Policy for Delhi, 2016) leading to a deficit of approximately 203 MGD. Such a situation calls for better and impactful engineering and governing solutions to bridge the gap.

Potential Water Resources
From the daily water supply to the Delhi population, nearly 80% of wastewater is generated. If this wastewater is discharged directly into the water bodies, it will degrade the water quality by several folds and may also have a negative impact on groundwater quality. While the city generates 733 MGD (3330 MLD) wastewater every day, the present operational sewage treatment capacity is about 600 MGD (2715 MLD) (CPCB, 2021) which is approximately 82% of the total sewage generated. While there is a gap between the sewage generation and the treatment capacity, it is important to realize that this gap was much larger until 2014 (less than 60%) and has been addressed to a great extent with the installed capacity of 2896 MLD. Thus, it is appreciable that the government has started to focus on treating wastewater in the capital city, a critical component of any sustainable solution for water and wastewater management.

Along similar lines, Delhi Jal Board in 2018 decided that all parks, complexes, and institutions will have Decentralized Sewage Treatment Plants (DSTPs) to reduce the dependence on groundwater; major parks and greenbelt areas, whether belonging to the Delhi government, Delhi Development Authority (DDA) or Municipal Corporation of Delhi (MCD) would not be allowed to use groundwater anymore. The step was meant to increase the success rate of recharging groundwater levels, improving ecology, and creating green public spaces. In 2021, the Delhi government, in consideration of DJB, had proposed to provide treated wastewater to the neighboring states in exchange for an equal quantum of drinking water.

Reusing Treated Wastewater
According to the CPCB, it is mandatory to release 267 MGD of treated wastewater into the Yamuna in order to abide by the Delhi government’s commitment to the Yamuna River Board. Apart from this, only 89 MGD is reused in the city while the rest of the treated water goes to waste. This quantum has to be increased effectively by reusing the treated wastewater for irrigation, in industries, or for water body rejuvenation. While the concept of wastewater treatment and the need to include it in all water supply and wastewater management programs is recognized by most policy frameworks and institutions, the aspect of supplying the treated water to potential users is the way forward. There is a need for proper monitoring and management system in order to provide treated water to potential users.

The potential resource also presents opportunities to recover nutrients and energy from wastewater. The recovery of phosphorus and potassium is particularly attractive as India imports most of its phosphorus and all of its potassium needs to meet demand (Water and Sanitation Program, 2016). The use of recycled wastewater for irrigation can help circumvent groundwater pumping and reduce both, freshwater and energy requirements for irrigation. Reduction in the use of energy also reduces GHGs, typically produced during the production and combustion of fuel and energy.

The Tariff Policy 2016 issued by the Ministry of Power mandates (under one of its clauses) that the thermal power plant(s) including the existing plants located within a 50 km radius of the sewage treatment plant of a municipality/local bodies/similar organization, shall in the order of their closeness to the sewage treatment plant, mandatorily use treated sewage water produced by these bodies. However, the potential of this policy has not been fully realized. In order to address the water issues of Delhi, it is suggested that such a policy be adopted for all industries as well as agricultural farms in and around the Capital to reduce the stress on the present water resources. Long-term wastewater reuse targets have to be set to sustainably address the water situation of the capital city.

The supply of treated wastewater to users would require the construction and alignment of separate conveyance systems. While the National Water Policy (2012) talks about the need for a proper tariff and incentives for providing treated wastewater to the users, it should be firmed up in the upcoming policies along with the inclusion and implementation of concrete norms for the supply and use of treated wastewater. In addition, users should be sensitized toward the utilization of treated wastewater which can be done through awareness and information generation programs.

About the Authors
Apoorva Bamal is a research associate, and Niyati Seth is an associate fellow with The Energy and Resources Institute (TERI). TERI is an independent, multi-dimensional research organization, with capabilities in policy research, technology development, and implementation.

Headquartered in New Delhi, TERI has regional centers and campuses in Gurugram, Bengaluru, Guwahati, Mumbai, Panaji, and Nainital, supported by a multi-disciplinary team of scientists, sociologists, economists, engineers, administrative professionals, and state-of-the-art infrastructure.

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