▽ +09.00Problem · Water tanks
The water tank is leaking
The water level drops without use, or damp shows around an underground tank or under a roof tank.
What you see
- The level drops when no water is used
- Damp walls or floors next to an underground tank
- Ceiling stains under a roof tank
- A cracked, peeling or blistered inner lining
- Water quality complaints: taste, colour or sediment
Possible causes
Cracks in walls or slab
Shrinkage, settlement or load cracks let water out.
A failed inner lining
Poor preparation, an unsuitable product or ageing.
Leaking pipe penetrations
Inlet, outlet and overflow pipes without proper sealing.
Wall-floor junction and construction joints
Well-known weak lines in tanks.
Leaking valves or pipes outside the tank
The tank may be sound while the network leaks.
How it is diagnosed
The diagnosis confirms the cause before any repair is chosen.
Level-drop test
Close the valves, mark the level and record the change over time.
Isolate the network
Confirm the loss is from the tank, not the pipes or valves.
Empty and inspect
Under confined-space controls: cracks, joints, penetrations and the lining.
Flood test after repair
The tank is filled and the level watched before it returns to service.
- Packer
- Crack
- Injected resin
- Surface seal
Possible solutions
The fix follows the diagnosis; these are the common options and their systems.
Injecting cracks and joints
To stop leaks through the depth of the concrete.
Systems
Repair and cementitious waterproofing
Repair mortar, then a cementitious system approved for drinking water.
Systems
Crystalline treatment
For sound concrete with fine cracks.
Systems
Epoxy lining
A smooth, hygienic lining with a potable-water approval.
Systems
What not to do
- Using products not approved for drinking water
- Coating a wet tank or over an active leak
- Entering a tank without ventilation and a confined-space procedure
- Refilling before the lining has cured and the tank is disinfected
General educational content; final values and requirements follow the manufacturer’s TDS and the approved project specification.
Common questions
Which approval should a drinking-water tank lining carry?
An approval for drinking-water contact from a recognised body — such as NSF/ANSI 61 or WRAS — applied and cured as approved; that is why not every epoxy will do.
Does the tank need to be emptied?
For internal repairs and linings, yes; the works are planned to keep the tank out of service as briefly as possible.
How can I tell if a water tank is leaking?
Fill the tank, close the valves and float overnight and measure the drop in level, or watch the meter with no consumption. Damp walls or soil nearby and insects gathering around the tank are other signs.
Technical inspection
Need a diagnosis for your case?
Send photos, a description and the location; our engineers identify the cause and the fix after an inspection.