Waterproofing a Water Tank in Ghana — Concrete, Reservoirs & Polytanks (2026)
Share
A leaking water tank in Ghana is usually one of three things: a crack in the concrete shell, a failed joint at a pipe penetration, or plumbing that has nothing to do with the tank at all. This guide covers the overnight test that tells you which, whether to repair from inside or outside, and exactly what to order.
First: Prove You Actually Have a Leak
This costs us a sale, so take it as honest. Before buying anything, do the overnight test.
- Fill the tank and mark the water level clearly on the inside wall.
- Close the outlet valve so nothing can be drawn off.
- Leave it 24 hours. No usage, no top-up.
- Check the mark.
Level dropped with the outlet closed? The tank is losing water through the shell. Read on.
Level held? Your tank is sound and the loss is in the pipework, a float valve, or an overflow. That is a plumber's job and considerably cheaper than waterproofing. A surprising number of "leaking tanks" turn out to be a float valve that never closes properly.
Outside or Inside?
Where the tank is accessible from outside, coat the outside. This is not a preference, it is physics.
Coating the external face is positive-side work — the water pressure inside pushes the membrane into the concrete, helping it stay bonded. Lining the inside is negative-side — pressure pushes against the back of the film and works to lift it off. Same product, same applicator, completely different odds of lasting.
Line the inside only when the outside genuinely cannot be reached — an underground reservoir, or a tank built hard against a boundary wall. See positive vs negative side for the full explanation.
How to Waterproof a Concrete Tank
- Drain it and let the concrete dry. Polyurethane will not bond to a damp surface, and a tank wall that has been wet for years takes longer to dry than you expect. This is the step people rush and the reason most tank coatings fail.
- Stop any active weeping with Plugging King (GHS 100) — it sets in seconds even against running water. Allow it to cure.
- Clean back to sound concrete. Remove algae, laitance, loose material and any failed previous coating. Nothing bonds to a dirty surface.
- Rake out and fill structural cracks with a flexible filler; let it cure.
- Tape the details — pipe penetrations, the wall-to-base junction, and any construction joint — with Leak Seal Tape (GHS 250). These are where tanks leak first.
- Two coats of polyurethane, the second perpendicular to the first, at about 1 kg per m² in total.
- Allow 24–48 hours to cure before refilling. Do not rush this because someone needs the water — an under-cured film is a failed film.
What to Order
Quantity at a glance
For a cylindrical tank, surface area is roughly height × circumference, plus the base if you are coating it. Multiply by 1 kg per m² for two coats — our measured consumption from completed jobs, not a label figure.
| Tank | Approx. area | Order | Cost |
|---|---|---|---|
| Small concrete, ~5,000 L | ~18 m² | 2 × 10kg | GHS 2,000 |
| Medium, ~10,000 L | ~30 m² | 3 × 10kg | GHS 3,000 |
| Large / underground reservoir | ~60 m² | 6 × 10kg | GHS 6,000 |
Add 10–15% on bare or rough concrete. Coating both faces? Double it. Send us your tank dimensions and we will work out the exact figure before you order.
| Product | Price | Role |
|---|---|---|
| Plugging King | GHS 100 | Stops active weeping in seconds so the surface can dry |
| Leak Seal Tape | GHS 250 | Bridges pipe penetrations and the wall-to-base joint |
| Polyurethane Coating/Paint 10kg | GHS 1,000 | The membrane. Two coats, 1 kg/m², 20-year design life |
→ Order Polyurethane Coating/Paint 10kg — GHS 1,000 | 5kg — GHS 500
Same-day dispatch in Greater Accra, nationwide delivery. 3-year manufacturer warranty.
Polytanks Are a Different Problem
Plastic tanks are not concrete. Coatings bond poorly to polyethylene, and a polytank under a full head of water flexes constantly.
- Small cracks, pinholes, fitting leaks: butyl tape (GHS 250) will hold, applied to a clean, dry, lightly abraded surface.
- A split of any real length: replace the tank. We would rather say that than sell you coating that will not stick.
Why Tanks Crack in the First Place
- Thermal movement — an exposed concrete tank in Accra heats and cools through a 20°C daily swing, and the water inside does not.
- Filling and emptying cycles — the shell flexes with the load every time.
- Construction joints — where a pour was interrupted, the joint is the weak line.
- Pipe penetrations — rigid pipe through moving concrete, almost always the first failure point.
- Reinforcement corrosion — once water reaches the steel it expands and pushes the concrete apart from inside. This is why a small leak left alone becomes a structural problem.
That last point is the argument for acting early. A crack you can seal this month becomes spalling concrete and exposed rebar in two rainy seasons.
Buying for a Drinking Water Tank
If the tank stores water for drinking, ask us for the product documentation before you order and we will send what we have from the manufacturer. Sensible practice with any coating from any supplier, and worth doing once so you have it on file.
Send Us the Dimensions
WhatsApp the tank's height and diameter, whether it is concrete or plastic, and whether you can reach the outside — 0555 548 001. We will tell you inside or outside, work out the exact quantity, and dispatch same day in Greater Accra.
Or book a free site assessment. Installed work carries a 3-year workmanship warranty and a 3-year manufacturer material warranty, with a 20-year design life on the membrane.