Rainwater Harvesting Systems in Nairobi & Kenya
Turn your roof into a free water source with gutters, first-flush diverters, filters, and storage sized to your roof and rainfall.
Every square metre of roof collects about one litre of water per millimetre of rain. A 150 m² roof in Nairobi, with roughly 850 mm of rain a year, can collect over 100,000 litres annually. With Nairobi Water tariffs rising by consumption block, harvesting for washing, flushing, gardens, and livestock pays back quickly. We design complete systems: gutters, downpipes, first-flush diverters, filters, tanks, and pumps.
What we do
Gutters & downpipes
PVC or galvanised gutters sized and sloped correctly, with leaf guards on every outlet.
First-flush diverters
Divert the first dirty rain away from the tank, keeping dust, droppings, and leaves out.
Storage tanks
Above-ground or underground tanks sized from your roof area and dry-season demand.
Filtration & treatment
Sediment filters, and UV or chlorination where water will be used for drinking.
Dual-supply switching
Automatic changeover between rainwater and county supply so you are never without water.
Garden & farm reuse
Pumps and lines to irrigation, greenhouses, and livestock troughs.
Rainwater harvesting costs in Kenya
Estimates for Nairobi. Costs depend on roof size, gutter length, tank size, and whether the water will be treated for drinking.
| System | Typical total (KES) | Includes |
|---|---|---|
| Starter kit – 2,300 L | 32,000 – 50,000 | Tank, gutters on one side, first-flush, tap |
| Home system – 2,000–5,000 L | 41,000 – 120,000 | Tank, base, piping, filter, first-flush, labour |
| Underground 10,000 L harvesting | 160,000 – 250,000 | Tank, excavation, pump, first-flush, plumbing |
| Gutters (installed) | 350 – 500 per metre | PVC gutters, brackets, outlets, downpipes |
| First-flush diverter | 3,000 – 12,000 | Depends on roof area and pipe size |
| School / church / farm system | Quote | Multiple tanks, large roofs, treatment |
Market estimates. Every job gets a fixed, itemised, VAT-inclusive quote after a site visit.
How much rain can your roof collect?
- Litres per year ≈ roof area (m²) × annual rainfall (mm) × 0.8.
- Nairobi (about 850 mm/year): a 100 m² roof yields about 68,000 L per year.
- Size the tank to carry you through the dry months, not just one storm.
- Use harvested water first for toilets, laundry, gardens, and cleaning. Treat it before drinking.
- Clean gutters and the first-flush chamber before each rainy season (March and October).
How it works
Roof & demand survey
We measure the roof, check the gutters, and work out the yield against your demand.
Design & install
We fit gutters, downpipes, first-flush, filters, and tanks.
Connect & hand over
We connect to taps, pumps, or dual supply and explain seasonal maintenance.
Frequently asked questions
How much does rainwater harvesting cost in Kenya?
A simple 2,300 L kit starts around KES 32,000–50,000. A complete home system with a 2,000–5,000 L tank costs about KES 41,000–120,000, and an underground 10,000 L system KES 160,000–250,000.
Is rainwater safe to drink in Kenya?
Not straight from the roof. With a first-flush diverter, sediment filter, and UV or chlorine treatment, rainwater can be made safe to drink. Untreated, it is ideal for toilets, laundry, gardens, and cleaning.
How big should my rainwater tank be?
It depends on roof area, rainfall, and how long the dry season lasts. Many Nairobi homes use 5,000–10,000 L. Schools and churches with large roofs benefit from 20,000 L or more.
Do you install rainwater systems for schools and churches?
Yes. Large roofs on schools, churches, and halls collect huge volumes. We design multi-tank systems with treatment so the water can be used for washrooms and kitchens.
Can I connect rainwater to my existing plumbing?
Yes. We add a changeover so the house draws rainwater first and switches to county supply automatically when the tank runs low.
More water tank services
Get a quote for rainwater harvesting
Free site visit in Nairobi. Fixed, VAT-inclusive written quote with an ETR receipt on completion.