What is water tank waterproofing?
Water tank waterproofing covers reinforced concrete overhead tanks (OHT), terrace tanks and smaller storage tanks above ground. Inside, it means sealing cracks and sleeves and applying a coating safe for drinking water. Outside, it means repairing cracked concrete, protecting the walls and roof slab from weather, and sealing the junction with the terrace so leaks do not pass to the floors below.
For tanks below ground, see our UG tank waterproofing service.
Benefits
- Stops leaks that show up as terrace and top-floor ceiling dampness
- Drinking-water-safe internal coatings
- Weather protection for tank walls and roof slab
- Sealed inlet, outlet and overflow pipe sleeves
Common problems and applications
Problems it solves
- Water dripping from the tank base or side walls onto the terrace
- Damp ceilings in flats below the tank
- Leaking pipe sleeves at inlet, outlet and overflow
- Cracked tank roof slab letting rain and debris in
- Flaking internal plaster and rust-coloured water
Where it is used
- Overhead tanks on housing society terraces
- Staircase-roof (mumty) tanks
- Fire and domestic tanks on commercial roofs
- Tank compartments inside new buildings
Our water tank waterproofing process
Plan supply and clean
The supply is planned with the society, the tank is emptied, desilted and cleaned.
Inspect inside and out
Cracks, sleeves, spalling, the tank roof and the base junction are inspected and marked.
Repair concrete
Loose plaster and weak concrete are removed, reinforcement is treated and sections are rebuilt.
Seal cracks and sleeves
Leaking cracks are injected or sealed, and pipe sleeves are re-grouted and sealed.
Coat inside and protect outside
A potable-safe coating goes inside; an elastomeric or cementitious protective coating goes on exposed outer faces and the roof slab.
Cure, flush and refill
After curing, the tank is flushed as per the product instructions, refilled and checked for leaks.
Materials and systems used
- Potable-grade cementitious and crystalline coatings
- Inside surfaces in contact with drinking water.
- Elastomeric exterior coatings
- Weather and UV protection for outer walls and tank roofs.
- Polymer repair mortars
- Rebuilding spalled concrete and coving corners.
- Non-shrink grouts and PU sealants
- Sealing pipe sleeves and joints.
Products are selected from the approved specification. Coverage, thickness and curing follow the manufacturer's current data sheet.
Why professional waterproofing is important
Leaks from overhead tanks are frequently misdiagnosed. Societies re-waterproof the whole terrace when the source is a single pipe sleeve or a cracked tank wall. Correct diagnosis saves money and solves the actual problem.
Inside the tank, products must be safe for drinking water and properly cured before refilling. Exposed outer faces need a system that copes with sun and heat. A professional job treats both sides and the junction with the terrace.
Why choose us
- Accurate diagnosis
- We check whether the leak is from the tank, the sleeves or the terrace before recommending work.
- Potable-safe materials
- Internal coatings selected for contact with drinking water.
- Combined terrace and tank work
- When both need attention, we sequence them to avoid repeat disturbance.
- Minimal supply disruption
- Work is planned with the society to keep shutdown short.
Read more about our team and how we inspect and record work.
Frequently asked questions
Which coating is safe for drinking water tanks?
Only coatings certified for contact with potable water should be used inside drinking water tanks, typically crystalline or polymer-modified cementitious systems. The tank must be cured and flushed as the manufacturer instructs before it is refilled.
How do I know if the leak is from the tank or the terrace?
A tank leak continues when it has not rained and changes with the water level in the tank. A terrace leak follows rainfall. We confirm during inspection, sometimes with a controlled water test.
How often should an overhead tank be waterproofed?
There is no fixed interval. Inspect the tank during each cleaning; flaking plaster, damp patches outside or leaking sleeves are signs that treatment is due.
Can you work on PVC or plastic tanks?
Our work is on concrete and masonry tanks. Plastic tanks are usually replaced rather than repaired.
