While treated wastewater in India is often discharged into water bodies or used for non-essential purposes such as irrigating public parks, its reuse for more critical applications remains relatively uncommon.

With depleting freshwater sources, erratic rainfall patterns and growing water scarcity, it is imperative that India adapt innovative water management solutions.

Data from the Central Pollution Control Board reveals that only 28 percent of the total sewage generated is effectively treated and a mere 3 percent of this treated wastewater is used beneficially.

This represents a significant untapped resource that could help alleviate India's water security concerns.

The failure to reuse treated wastewater also underutilises the substantial capital invested in sewage treatment plants.

But without adequate infrastructure, supportive policies and financial incentives, this situation is likely to continue.

Existing challenges

Despite the growing need, wastewater reuse in India faces several challenges.

The infrastructure for wastewater treatment is inadequate.

There is an absence of guidelines on sector-wise quality of treated water reuse as different sectors have distinct requirements of processed water quality ranging from biological treatment to reverse osmosis or ultrafiltration to meet quality standards.

R&D initiatives are deficient and require boosting of investment to foster innovation and accelerate the adoption of wastewater reuse practices. There is also a lack of participation by the private sector and a lack of skilled personnel.

Added to this, socio-cultural barriers often prevent the acceptance of reused water.

The high capital costs of setting up wastewater treatment facilities and advanced technologies, such as zero liquid discharge which maximises the water being recovered for reuse but is also very expensive, discourage industries and municipalities from embracing reuse practices.

Financial constraints and a lack of clear incentives further hinder progress.

Benefits of water reuse

This is despite the many benefits of reusing wastewater.

Reusing treated wastewater is a promising solution to freshwater scarcity.

For example, a large-scale project of using treated wastewater for agriculture and groundwater recharge in Kolar, Karnataka, demonstrated significant socio-economic benefits.

The results showed improved groundwater levels and quality, increased agricultural productivity, higher livestock and fish production, and a 118 percent rise in land values.

The net income of farmers from cash crops doubled, highlighting the project's potential to boost agro-economic systems and support a circular economy in the water sector.

A study by The Energy and Resources Institute in thermal power plants suggested that interventions such as ash water recirculation and implementing wastewater recycling and reuse can yield a collective average monetary benefit of on average Rs 300 million per year ($US3.57 million) with accompanying water savings of nearly 10 million cubic metres a year.

Another study by the institute found that the Bangalore Water Supply and Sewerage Board generates an additional annual revenue of nearly Rs 164 million ($US2 million) by selling 18 million litres per day of treated water, which entirely covers its operations and maintenance costs.

A similar model operates in Chennai and could be replicated all over India.

There are also benefits to be gained from recycling the valuable nutrients found in wastewater — like nitrogen, phosphorus and potassium — which if recovered can be used to reduce reliance on synthetic fertilisers.

The International Water Management Institute estimates that the sewage generated from class I and II cities across India — 6,400 million litres per day according to the Central Pollution Control Board — has a nutrient load of about 2,500 tonnes.

This translates into a theoretical daily monetary value of Rs 19.5 million ($US232,000) if the nutrients have a value of Rs 8,000 ($US95) per tonne.

Driving the change

While several Indian states have implemented policies to promote treated water reuse, a comprehensive national framework is essential to drive widespread adoption.

The National Mission for Clean Ganga took a significant step in this direction by publishing the "National Framework on Safe Reuse of Treated Water" in 2022.

This framework outlines the roles of various government agencies and proposes business models to encourage treated water reuse.

However, more robust policies and incentives are necessary to fully integrate treated water into India's hydrological cycle, such as:

1. Setting up water reuse benchmarks for industries

In the absence of well-defined standards for treated water usage, it is essential to equip industries with a clear set of guidelines and established benchmarks. This could include standards based on a fit-for-purpose approach to promote wastewater reuse and resources recovery, without compromising on product quality.

2. Incentives for R&D in water efficiency and wastewater reuse

The government should implement policies that incentivise industries, research institutions and universities to undertake R&D initiatives focused on innovative water treatment technologies, water efficiency practices, pilot projects and demonstrations.

3. Incentives for agriculture

Farmers may be incentivised to use treated wastewater for irrigation, especially in water-scarce regions.

4. Volumetric water pricing

Water users should be charged different rates based on their level of consumption. Higher tariffs for non-recycled water will encourage municipalities and housing societies to adopt recycled water for non-potable purposes.

5. Incentive for housing societies and residential areas

Encourage the use of treated water for non-potable purposes such as landscaping, toilet flushing and cooling systems in residential areas. This could be done by subsidising dual plumbing systems to separate potable and non-potable water supplies or providing rebates on property taxes as a reward for reducing dependency on freshwater.

6. Public-private partnerships

Engaging the private sector as a partner can fast track the development of wastewater treatment and reuse infrastructure. The government can provide financial support, while the private entities bring in technical expertise to build and maintain the systems.

7. Water use credits

Similar to carbon credits, entities that use treated wastewater could receive water-use credits, which could be monetised or traded with other developers. The 2030 Water Resources Group hosted by World Bank Group has published a handbook on wastewater reuse certificates as tradable permits which can be used as a base document for such a policy intervention.

India stands at a pivotal moment in addressing its escalating water challenges.

With 72 percent of sewage remaining untreated and more than 35,000 million cubic metres of treated wastewater expected to be available by 2050, the opportunities for large-scale wastewater reuse and related socio-economic benefits are substantial.

By easing financial constraints, offering regulatory support and cultivating a market for treated wastewater, the government can drive widespread adoption of reuse practices.

This shift will not only alleviate pressure on freshwater resources but also enhance water security and sustainability for future generations.

Anshuman is Director, Water Resources Division of The Energy and Resources Institute (TERI) in New Delhi, India.

This article is part of a special report on water reuse, produced in collaboration with The Energy and Resources Institute (TERI), New Delhi.

Originally published under Creative Commons by 360info™.

Simply Put: To use groundwater, recharge