Underground Water Tank Construction in Nairobi & Kenya
High-capacity storage that stays hidden, keeps water cool, and frees up your compound, from 5,000 L to 200,000 L+.
Underground tanks are the best way to store large volumes on tight plots. The water stays cool and dark, which limits algae, and the tank is protected from sun and theft. They suit homes in Kilimani, Lavington, and Karen, apartment blocks, and institutions that need days of reserve. We build in reinforced concrete, install buried polyethylene tanks, or use membrane-lined reservoirs for very large capacities.
What we do
Excavation & shoring
Safe excavation with shoring where soil is loose, plus de-watering in high water tables like Embakasi.
Reinforced concrete tanks
Grade 25–30 concrete with steel reinforcement and food-grade waterproof lining, built for 30–50 years.
Buried poly tanks
Purpose-made underground polyethylene tanks with a concrete surround and anti-flotation slab.
Membrane reservoirs
HDPE geomembrane-lined reservoirs for 50,000–200,000 L, at lower cost than full concrete.
Pumps & level controls
Submersible or surface pump, float switch, and dry-run protection to lift water to the house or tower.
Access & safety
Lockable manhole covers, vent pipes, and overflow so the tank is safe and easy to clean.
Underground water tank costs in Kenya
Estimates for Nairobi including excavation and basic fittings. Rock, water-logged ground, or deep tanks can add 20–40%.
| Type & size | Typical total (KES) | Notes |
|---|---|---|
| Buried poly tank – 10,000 L | 140,000 – 190,000 | Quickest option; needs anti-flotation slab |
| Buried poly tank – 20,000 L | 220,000 – 290,000 | Often two tanks linked |
| Concrete tank – 5,000 L | ≈ 155,000 | Excavation, concrete, waterproofing, fittings |
| Concrete tank – 10,000 L | ≈ 260,000 | Most common home size |
| Concrete tank – 20,000 L | ≈ 435,000 | Apartments, schools, churches |
| Membrane reservoir – 50,000–200,000 L | 500,000 – 2,000,000 | Farms, estates, institutions |
Market estimates. Every job gets a fixed, itemised, VAT-inclusive quote after a site visit.
Concrete or plastic underground tank?
- Poly tanks are faster (2–4 days) and cheaper at small sizes, but must be anchored against flotation.
- Concrete lasts 30–50 years, can be any shape to fit your plot, and works out cheaper per litre above about 20,000 L.
- In high water-table areas we design for uplift and use waterproof additives in the concrete.
- Always fit a lockable cover and keep the tank away from septic tanks and soak pits (at least 15 m).
How it works
Soil & site check
We locate services, check soil and the water table, and agree the tank position.
Excavate & build
We excavate, cast or place the tank, waterproof it, and backfill in compacted layers.
Plumb & commission
We fit the pump, controls, and pipework, then fill, leak-test, and hand over.
Frequently asked questions
How much does an underground water tank cost in Kenya?
A 10,000 L buried poly tank costs about KES 140,000–190,000 installed, and a 10,000 L reinforced concrete tank about KES 260,000. Large 50,000–200,000 L membrane reservoirs run KES 500,000–2 million.
How long does it take to build an underground tank?
Buried poly tanks take 2–4 days. Concrete tanks take 10–14 days, including curing, before they can be filled.
Do underground tanks need a pump?
Yes. Water must be lifted to the house or an elevated tank. We fit a pump with float and dry-run protection so it switches off automatically.
Can an underground tank be used for rainwater?
Yes. Underground tanks are ideal for rainwater harvesting because they store large volumes cool and out of sight. We add gutters, a first-flush diverter, and a filter.
Will an underground plastic tank float?
An empty tank in wet ground can be pushed up by groundwater. We prevent this with a concrete anti-flotation slab and correct backfill.
More water tank services
Get a quote for underground tanks
Free site visit in Nairobi. Fixed, VAT-inclusive written quote with an ETR receipt on completion.