What should you do about a water leak under your floor or house?
Turn off the water at the stopcock, isolate electrics if water is near them, and get a plumber or leak-detection specialist to find and stop the leak. Report it to your insurer promptly, as hidden under-floor leaks can be covered, and check whether your policy includes trace and access cover for the cost of locating the leak. Document everything and avoid pulling up floors yourself before the insurer has advised on the process.
Leaks under a floor or beneath the property are tricky because the water is out of sight and can cause a lot of damage before you notice it, showing up as a warm patch of floor, an unexplained rise in your water bill, the sound of running water, or damp and musty smells. If you suspect one, turn off the mains stopcock and, if there is any chance water has reached wiring, isolate the electrics and keep clear.
Locating a hidden leak is a job for a professional using non-destructive leak detection rather than guesswork that means ripping up floors. This matters for your claim because many policies include trace and access cover, which pays the cost of finding and getting to the leak, for instance lifting flooring, as well as putting it back afterwards. Check whether you have this cover before work starts.
Report the situation to your insurer promptly. Damage from an escape of water, meaning water escaping unexpectedly from pipes or fittings, is commonly covered even when the leak was hidden, provided it is sudden rather than the result of long-term neglect. Do not assume you are not covered just because the leak was slow to reveal itself; the sensible reading of most policies is that you claim promptly once you discover it.
Keep strong evidence, because under-floor claims are often questioned on cause. Get the plumber's or leak-detection report in writing, stating what failed and where, and take photos of the damage and the exposed pipe once it is found. Keep receipts for detection, drying and repair. This documentation is what separates an accepted hidden-leak claim from a disputed one.
Watch out for two things insurers scrutinise: whether the leak was gradual wear and tear, which is usually excluded, and whether the resulting damp or rot built up over a long period. Neither automatically defeats a claim for the sudden escape itself, but they are common reasons for a low offer or refusal, so professional evidence on cause is worth having. If your cover is unclear, check your policy wording or get the claim reviewed.
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This is general information about UK home insurance claims, not financial or policy-specific advice. Always check your own policy wording.