Enabling easy-to-operate decentralized domestic wastewater treatment systems to increase reuse rates

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Problem Overview: Low Reuse and Recycling Rates of Wastewater

India generates 72.4 billion liters of wastewater, but only 28% of it is treated and only ~3% is recycled [1,2]. With increasing water stress and falling groundwater levels, there is a need for treatment and reuse of wastewater to meet the demands and improve water security. Additionally, poorly managed water treatment system can result in high greenhouse gas emission, namely as N2O and CH4 emissions. Upcoming regulations on wastewater treatment are focussing on on-site decentralized treatment and reuse mandates. The regulation varies with state and type of industry, but most commercial wastewater generators are required to treat and reuse their wastewater. With current wastewater treatment techno-economics, there are limitations on reuse efficiency and use-cases, which hinder a truly circular water cycle.

Core Bottlenecks: Suboptimal operations and limited reuse options

With the new regulations, bulk wastewater generators (commercial and residential buildings) have adopted decentralized Sewage Treatment Plants, which focus on primary and secondary treatment of water, using technologies like MBBR, SBR or MBR, followed by disinfection and reuse for flushing or irrigation. Users face two key challenges:

1. Biological solutions: Fragile & hard to operate

Microbes often die if there is input fluctuation, delicate membranes are easily destroyed, leading to poor quality of treatment. Operations suffer from severe skill gaps, with operators often not being trained to handle advanced technological solutions. Hence, the systems are not running at their optimal conditions

2. Non-Human Contact Reuse Only

Common solutions only take water to a level of purity suitable for non-human contact uses (e.g. flushing, gardening), not for other uses without the use of RO. This leads to treated wastewater being used for excess irrigation, which is not ideal and does not encourage higher recycling rates. Additionally, many existing facilities do not have alternate flushing lines which further hinders wastewater reuse [3].

Existing Approaches and Technology Readiness

Automation and Optimization

Reduces energy usage, increases water quality

Electrocoagulation

Reduces reliance on biological systems, ensuring reliable & space-efficient operations

Water-less flushing

Reduced water usage to eliminate problem at source

Where is the white-space for innovation?

The technologies and solutions above, which if implemented at scale, can enable reliable and space-efficient treatment systems. However, the reuse rates for use cases beyond flushing and irrigation remain limited without use of expensive technologies like RO. The scope for innovation is on three fronts:

science-icon.svgScience Breakthrough

Alternative to RO technology that can achieve low TDS output without reject waste stream.

briefcase.svgEngineering Innovation

Space-efficient, odorless, automated decentralized water treatment systems that can reliably produce usable water for reuse beyond flushing & gardening applications.

briefcase.svgBusiness model

Enabling offsite usage for treated non-potable water.

How we identify climate innovation opportunities?

Our methodology
Footnotes
  1. Gupta, S. et al., 2025, Financing Treated Used Water Reuse in India, Council on Energy, Environment and Water
  2. Jones, E. R. et al., Country-level and gridded estimates of wastewater production, collection, treatment and reuse, Earth Syst. Sci. Data
  3. Well Labs, 2025 Report, Strategies to Catalyze Safe, Efficient and Reliable Decentralized Water Reuse 
  4. Calculated based on energy saving from automated systems and reduced pumping energy for water
  5. Calculated based on reduction in CH4 and N2O emissions, as well as reduced water pumping energy  
  6. Calculated based on adaptation potential from increasing water access

MBR = Membrane Bioreactor, MBBR = Moving Bed Biofilm Reactor, SBR = Sequencing Batch Reactor

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Author: Bharti Singhla

Last Updated On: June 5, 2026

Economic Potential

  • India, 202581Mn USD[4]
  • India, 2030~150Mn USD[4]

Impact Potential

  • India, 202555 Mn Mt CO2e[5]
  • Lives Impacted (domestic water supply)0.22-0.54 Mn people
  • India Score9/27[6]
  • Hazard
  • Exposure
  • Sensitivity
  • Adaptive Capacity
  • Vulnerability
Low Med High
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WaterWater BiodiversityBiodiversity WasteWaste

p-ARL Score

10/12

  • 0
  • 1
  • 2
  • 3
Regulation & Policy Force
Economic Switching Cost
Infrastructure Readiness
Value Chain Consensus

Regulatory Outlook

National Framework on Safe Reuse of Treated Water (SRTW) GuidelineGuideline
SPCB’s Decentralized Treatment Mandate for bulk wastewater ImplementedImplemented

Spotlight for innovation in India

Startups

Digital Paani: Automating operations to reduce energy and improve quality.

IndraWater: Patented Electrocoagulation system to avoid biological pathways

EkamEco: Waterless Urinal to reduce water usage in flushing

Scope of Innovation

Footnotes
  1. Gupta, S. et al., 2025, Financing Treated Used Water Reuse in India, Council on Energy, Environment and Water
  2. Jones, E. R. et al., Country-level and gridded estimates of wastewater production, collection, treatment and reuse, Earth Syst. Sci. Data
  3. Well Labs, 2025 Report, Strategies to Catalyze Safe, Efficient and Reliable Decentralized Water Reuse 
  4. Calculated based on energy saving from automated systems and reduced pumping energy for water
  5. Calculated based on reduction in CH4 and N2O emissions, as well as reduced water pumping energy  
  6. Calculated based on adaptation potential from increasing water access

MBR = Membrane Bioreactor, MBBR = Moving Bed Biofilm Reactor, SBR = Sequencing Batch Reactor

Profile.svg
Author: Bharti Singhla

Last Updated On: June 5, 2026