FREQUENTLY ASKED QUESTIONS
What is greywater?
Greywater is a lightly polluted wastewater that is generated from activities such as showering/bathing, laundry and handwashing. It is different from blackwater that comprises of toilet and kitchen wastewater.
How much greywater is generated per household?
As per Indian Standard 1172: Code of Basic Requirements for Water Supply, Drainage and Sanitation Greywater generation for urban and semi-urban residents is estimated as 100 litres per person per day.
What does greywater consist of?
Greywater generated from activities such as shower and laundry primarily consists of suspended solids (dirt, hair, fibre, lint, etc.) The greywater also has dissolved soap as well as other chemicals.
Does greywater contain harmful pathogens?
Greywater generated due to bathing and cloth washing may have faecal contamination with the associated pathogens and parasites such as bacteria. However, the concentration of these pathogens is significantly lower compared to raw sewage.
Why should greywater be recycled and reused?
Greywater largely contains suspended particles with very low concentration of pathogens and dissolved substance. It can be treated with simplified techniques such as physical filtration followed by small chemical treatment. On the other hand, sewage or blackwater requires significant treatment including biological process.
What does greywater treatment comprise of?
Greywater is treated with multiple stages of filtration followed by disinfection and aeration. Read detailed description here.
Which buildings and facilities can benefit from greywater recycling?
- Individual houses
- Apartment buildings
- Hostels and Guest Houses
- Hotels and resorts
- Public washrooms and toilets
- Any other facility where significant amount of greywater is generated
For which applications can the treated water be used?
- Flushing of toilets and urinals
- Gardening and landscaping
- Floor washing
- Construction activities