Bridging the gap: Unlocking the potential of treated wastewater in India’s water crisis

Reusing treated water has long been a part of traditional practices, with past generations using it for horticulture and daily needs. However, rising populations have driven water demand and wastewater generation to unprecedented levels.

India generates over 72,000 million litres per day (MLD) of sewage, but only 28 per cent is treated and even less is reused. Untreated wastewater continues to pollute rivers, lakes and groundwater, exacerbating the water crisis. With just 4 per cent of the world’s freshwater, India sustains 18 per cent of the global population. By 2030, water demand is set to double and per capita availability may drop below 1,200 cubic metres by 2050.

Cities like Delhi, Bengaluru and Chennai already face severe water shortages, relying on distant sources. Groundwater depletion is critical, with over 70 per cent of aquifers in stressed or over-exploited conditions, particularly in Punjab, Haryana and Rajasthan. This threatens food security, economic growth and public health, placing India among the world's 13 most water-stressed nations.

Sustainable solutions are imperative. The principles of reduce, reuse, recycle (3Rs) and rejuvenate, respect (2Rs) are key to securing water for the future. Treated wastewater offers a viable alternative, with large volumes readily available to supplement supply.

A recent report, Waste to Worth: Managing India’s Urban Water Crisis through Wastewater Reuse, by Delhi-based think tank Centre for Science and Environment (CSE) and the National Mission for Clean Ganga, highlighted wastewater’s potential for irrigation, industry and urban greening.

The report emphasised the potential of wastewater reuse, stressing the critical importance of prioritising treated wastewater as a public good, especially for irrigation and groundwater recharge. Additionally, it highlighted the need to ensure equity and justice for underserved communities, alongside its use in industries.

Waste to Worth advocated for a fundamental shift in policy and practice from a linear water economy to a circular economy model, where water is reused and recycled in a sustainable loop. It analysed the current national and state-level status and policy actions concerning the reuse of treated wastewater.

A reality check

A detailed study conducted by CSE examined case studies across seven states — Haryana, Delhi, Uttar Pradesh, Rajasthan, Maharashtra, Tamil Nadu and Karnataka. It documented 35 case studies across 16 cities and showcased varied practices.

Cities like Bengaluru were found to demonstrate the value of linking water supply, treated wastewater, lakes and aquifers to re-imagine urban water supply and wastewater management for the cities of the future.

But the report also highlighted key ground realities.

Haryana has adopted an Integrated Water Resources Action Plan (IWRAP), ensuring systematic wastewater reuse. With 1,965 MLD available for reuse, the state has a structured action plan for 2023-25, covering all districts and sectors.

In Delhi, the 2016 Draft Water Policy promotes decentralised reuse of treated wastewater, but implementation remains slow. Co-locating sewage treatment plants (STP) with parks and lakes has shown potential for reuse.

In Karnataka, Bengaluru holds 50 per cent of the state’s sewage treatment capacity, offering the highest reuse potential. The city effectively reuses treated water for lake rejuvenation and groundwater recharge.

In Tamil Nadu, despite lacking a clear action plan, Chennai leads in reuse through a PPP model, supplying costly tertiary-treated water to industries. However, targets for expanding reuse infrastructure remain unmet.

Maharashtra needs a well-defined reuse policy with clear targets and timelines. Cities like Nagpur, Pune and Mumbai have made progress, but many STPs still fail to meet discharge standards.

Treated water reuse is primarily for industrial purposes in Rajasthan, helping industries secure water rights. However, there is a risk of monopolisation and equity concerns must be addressed.

In Uttar Pradesh, despite generating 5,500 MLD of sewage, only 3,296 MLD is treated, with reuse primarily limited to agriculture. Quality issues, governance gaps and the absence of a structured reuse plan hinder large-scale adoption.

Bottlenecks in mainstreaming reuse of treated wastewater

India lacks a national mandate for wastewater reuse, relying instead on a general framework. Only 11 out of 28 states have reuse policies, most without clear action plans. Compliance is weak — just 17 per cent of treated wastewater meets Central Pollution Control Board (CPCB) standards. 

In Delhi, 21 out of 37 STPs fail to comply, while in Maharashtra, 80 out of 147 fall short. Poor monitoring allows non-compliant STPs to discharge substandard effluents unchecked. Existing CPCB and National Green Tribunal (NGT) regulations focus on wastewater discharge rather than reuse applications. Haryana has specific reuse standards, but national adoption remains limited.

Infrastructure gaps further hinder reuse. Many STPs are far from reuse sites and decentralised plants are underdeveloped. Large centralised STPs lack conveyance infrastructure, while high tertiary treatment costs restrict reuse, particularly in Tamil Nadu and Maharashtra. 

Wastewater reuse is largely city-centric — Gurugram accounts for 50 per cent of Haryana’s reuse, while Bengaluru and Chennai lead in Karnataka and Tamil Nadu. Smaller towns lack structured plans and agricultural reuse (46 per cent) remains underutilised despite its potential to reduce freshwater dependence.

Fragmented governance complicates reuse efforts, with multiple agencies managing water and wastewater separately. While Haryana’s IWRAP and Karnataka’s Wastewater Reuse Resource Centre offer structured models, most states lack similar frameworks. Public resistance, particularly in agriculture, remains a challenge. Concerns over soil quality prevent wider adoption, as seen in Rajasthan, where farmers reject reuse despite its proven benefits.

Policy and infrastructure key

Reusing treated wastewater from STPs not only adds a significant volume of “new water” but also ensures adherence to treatment standards and continuous compliance monitoring. This approach makes treated water users key stakeholders in maintaining quality standards. 

However, large-scale wastewater reuse remains limited due to regulatory gaps, financial constraints and public resistance. Scaling up reuse requires key interventions, starting with a national policy mandating reuse across industries, agriculture and urban applications. Currently, only 11 out of 28 states have reuse policies, most of which lack clear action plans.

Effective reuse must begin with proper sewage and septage management, ensuring STPs meet CPCB discharge standards before reuse. City-wide planning is crucial, as most STPs were not originally designed with reuse in mind. 

Treated wastewater should be prioritised for irrigation and groundwater recharge through lake and waterbody rejuvenation. However, infrastructure remains a major barrier, requiring investment in transport systems, decentralised treatment in smaller towns, subsidies, tax incentives and viability gap funding.

State-level policies must define priorities, enforce time-bound implementation with monitoring and move beyond utility-level projects to broader strategic planning. Policies should be tailored to local wastewater generation patterns, supported by strong institutional frameworks. Current CPCB and NGT regulations focus on discharge rather than reuse, necessitating sector-specific standards. 

Public acceptance is another challenge, particularly in agriculture, where concerns over hygiene and safety hinder adoption. Awareness campaigns, pilot projects and incentives can help shift perceptions, while urban planning should integrate reuse, following models like Delhi’s Draft Water Policy, 2016.

The private sector can play a critical role in scaling reuse through public-private partnership or PPP models, as seen in Chennai and Nagpur. Strengthening institutional mechanisms, such as Haryana’s Water Reuse Authority, will be essential for effective implementation.

This blog is the first in a series exploring case studies from the Waste to Worth report.