Reuse and Circularity

Urban areas are rapidly expanding worldwide, especially in the Global South. Water security is a critical challenge for these urban populations. According to a WWF scenario analysis in November 2020, areas of high water risk could increase to 51% by 2050,  up from 17% in 2020. This is particularly concerning for India, where half of the population is projected to be urban by 2050. As of 2019, 600 million people in India already face high to extreme water stress and by 2030 demand is expected to outstrip supply twice. With only 4% of the world’s water resources, India must support 18% of the global population. Additionally, 50% of the country’s aquifers are estimated to reach critical levels by 2040, highlighting the severity of India’s water crisis.   

Potential For Water Resuse

Urban areas, especially in the Global South, are expanding rapidly. This growth brings increasing pressure on water resources, making water security a pressing concern. According to WWF’s 2020 scenario analysis, regions facing high water risk could rise from 17% in 2020 to 51% by 2050. In India, this is particularly alarming—by 2050, nearly half the population is expected to live in cities. Already, over 600 million people face high to extreme water stress, and by 2030, the national demand is projected to be twice the available supply. With just 4% of the world’s freshwater resources supporting 18% of the global population, India must adopt circular approaches to manage water more sustainably.

Unlocking the Potential of Wastewater Reuse

Treated wastewater has immense potential to meet irrigation and industrial demands. In urban neighbourhoods and residential complexes, 20–40% of wastewater can be reused for flushing and landscaping. Yet, less than 10% of India’s wastewater is currently reused—posing both a challenge and a significant opportunity.

Reusing treated wastewater:

  • Reduces freshwater extraction, helping to conserve critical water reserves.
  • Lowers energy use and GHG emissions, especially from groundwater pumping and long-distance water transfers. Studies suggest that wastewater reuse in Indian agriculture could reduce over 1 million tonnes of CO₂-equivalent emissions.
  • Improves affordability, reducing the financial burden of water supply systems.

Decentralised and Context-Specific Treatment

Reuse becomes more viable and cost-effective when treatment happens close to the source. As the distance increases, the feasibility and economics of reuse become challenging. Therefore, decentralised treatment infrastructure—tailored to local demands for irrigation, industry, landscaping, recharge, and flushing—is crucial.

Instead of standardised systems, context-specific treatment technologies should be promoted. Current decisions are often driven by capital expenditure alone, overlooking long-term sustainability and adaptability.

While India has a wide range of treatment technologies, conventional systems dominate. Policies on wastewater reuse remain fragmented and lack holistic implementation. A shift in both planning and governance is essential to unlock the full potential of reuse and ensure long-term water security.

Tapping the Value of Treated Sludge

India’s sewage treatment plants generate a large volume of sludge—over 100,000 tonnes annually, according to MoHUA data. With 50% treatment coverage, this could rise to 186,000 tonnes. Rich in nutrients like nitrogen, phosphorus, and potassium (NPK), treated sludge can replace up to 4,500 tonnes of urea per day, offering a sustainable alternative to chemical fertilisers.

  • Supports soil health: India’s average soil organic carbon content is just 0.3%, far below healthy levels.
  • Enhances crop yield: Especially critical for small farmers grappling with high input costs and water scarcity.
  • Reduces GHG emissions: Sustainable fertiliser alternatives can mitigate the climate impacts of industrial agriculture.
  • Addresses future shortages: With global phosphorus reserves depleting, sewage sludge offers a viable alternative.
CDD India’s Commitment to Resource Recovery

For over 20 years, CDD India has championed resource recovery from human waste through its flagship initiative: Closing the Loop.

Key examples include:

  • Treated water reuse for flushing in multi-apartment buildings.
  • Suvidha Centre @ Ghatkopar, where treated greywater supports community toilet facilities in informal settlements.
  • Co-composting at Devanahalli FSTP, enabling safe sale of treated faecal sludge.
  • Urban greening through the reuse of treated water in over 100 landscape and garden projects.
  • NEXUS approach linking sanitation with food and water security for small communities.
  • Phosphorus recovery research from treated wastewater for circular fertiliser use.