📋 In This Article
Greywater — wastewater from sinks, showers, and washing machines (not toilets) — makes up 50–80% of household wastewater. Treating and reusing it for garden irrigation can reduce household water consumption by 30–50%.
What is Greywater and Is It Safe?
Greywater contains soaps, skin cells, and small amounts of bacteria but no fecal matter. When applied to soil for plant irrigation (not directly to food crops), it is generally safe and beneficial. Soil microbes break down organic matter and pathogens within 24–48 hours. Using greywater on fruiting crops, trees, and ornamental plants is widely practiced.
Simple Greywater Collection
The simplest system: keep a bucket in the shower to catch warm-up water while waiting for hot water, and use this directly on garden plants. A bucket under the kitchen sink catches rinsing water. Washing machine outlet pipes can be redirected to a garden mulch bed.
Basic Treatment Systems
A constructed wetland (a lined shallow bed of gravel planted with reeds and water-tolerant plants) passively treats greywater through biological processes. A simple sand filter through which greywater passes before reaching plants removes most bacteria and suspended solids. These systems cost ₹5,000–20,000 and last for decades.
Legal and Practical Considerations
Greywater reuse is legal in India for garden irrigation. Use a mulch basin (a ring of organic mulch around the drip point) to prevent runoff and allow even absorption. Do not spray greywater (aerosols carry pathogens). Apply to soil, not directly to plant leaves or edible parts. Avoid storing greywater for more than 24 hours — it becomes anaerobic and odorous.
Conclusion
In India's water-scarce context, greywater reuse is a practical, low-cost contribution to household water security. A bucket in the shower costs nothing and saves hundreds of litres per week.