Evidence-based best practices and benchmarks for grey water circularity

Barth F. Smets

Professor of Environmental Microbiology, Department of Environmental Engineering, Water Technology & Water Processes; Technical University of Denmark (DTU)

Abhayraj Naik

Co-Founder - Initiative for Climate Action (ICA)

Arnaud Dechesne

Senior Researcher, Department of Environmental Engineering, Water Technology & Water Processes; Technical University of Denmark (DTU)

Saurabh Shresth

Global R&D Director; Hindustan Unilever Limited (HUL)

Prashanth N Srinivas

Assistant Director Research - Institute of Public Health (IPH), Bengaluru

Nimish Shah

Managing Director - India, TBC; Toilet Board Coalition (TBC), India Chapter

Priyanka Jamwal

Fellow, Centre for Environment and Development; Ashoka Trust for Research in Ecology and the Environment (ATREE)


There is a lack of centralized infrastructure for wastewater treatment in both domestic & industrial sectors as well as a lack of sufficient sanitation systems and plastic collection and recycling. There are also issues related to consumer behaviour on how to discard waste and polluted water, and there is an associated lack of monitoring and enforcement of policies for water treatment and discharge to freshwater water sources. All these factors have led to risks to human health, groundwater contamination, negative impacts on biodiversity, an increase in antimicrobial resistance (AMR) and more non-biodegradable waste in our water bodies, such as plastic. To address these issues, we need to understand how we can reduce degradation and promote reuse contaminated and polluted surface water (grey water).


1. Identify the social, political, health, climate and economic input and output parameters for circular solutions for greywater, esp. Nature-based.
2. Identify the water quality criteria required for various types of greywater use and reuse.
3. Demonstrate based on comprehensive review of technologies and existing solutions an efficient solution (based on assessment of defined parameters) for greywater circularity through in selected test sites.
4. Based on the previous results, elucidate the principles underlying effective circular greywater solutions that can be deployed in communities.
5. Establish clear criteria and benchmarks for products/solutions for greywater circularity in India as a basis for motivating behavioural change in producers, consumers, and decision makers.


1. Improved water security within rising water stress and reduced per capita availability.
2. Fits well with Govt. of India’s intent to provide tap water to all households by 2024. Providing water needs to go hand-in hand with water saving practices.
3. Communities can mitigate economic and climate- related issues from water loss and transport and reduce the water footprint.
4. Can develop implementable solutions for addressing water borne disease and AMR with circular water systems.
5. Standards and Criteria will be developed for greywater circularity to be implemented and scaled up by entrepreneurs.
6. Can provide economic, social, and environmental incentives for communities to adopt circular greywater strategies.
7. Can provide research in practice to link academic, industry, government, and community goals regarding wastewater, AMR, and related issues for efficient circular water systems.