Why a small leak never stays small

A dripping tap or a slow weep from a pipe joint is easy to live with: it's quiet, it's small, and it isn't flooding anything — yet. The US EPA's WaterSense programme put hard numbers on "small": the average household's leaks waste more than 10,000 gallons a year, a faucet dripping once per second alone wastes more than 3,000 gallons — about 180 showers' worth — and one home in ten has leaks running 90+ gallons a day. And the water bill is the smallest of the leak's costs.

Why leaks escalate

A leak is a mechanism, not a state. The worn washer that lets a tap drip also lets water work on the valve seat, so the drip sharpens; the weeping joint corrodes the very metal it touches; the loosened flapper in the cistern lets water run silently for months — toilet flappers are the EPA's most-cited household leak for exactly that reason. Water follows gravity through whatever it reaches: a slow leak under a sink first swells the board floor, then rots it, then feeds the mould that turns a £4 washer into a cabinet rebuild. Out of sight behind a wall, a pinhole supply leak is how you meet the damp-diagnosis guide from the worst possible direction.

The insurance wrinkle nobody mentions

Most home policies draw a hard line between sudden water damage (a burst pipe — typically covered) and gradual damage (a leak that's been seeping for months — often excluded, and insurers look for exactly that evidence). That's not legal advice and policies differ, but the asymmetry is real: the slow leak you mean to fix next month can land entirely on you, structure and all, while the same leak caught this week is a small claim or no claim at all. Check your own policy's wording once — it's five minutes that can be worth thousands.

Finding the silent ones: the meter test

The EPA's own method: read your water meter, don't use any water for two hours, read it again. Movement means a leak you haven't met yet. For toilets — the classic silent runner — a drop of food colouring in the tank that appears in the bowl without flushing means the flapper's gone. Then walk the house: under every sink, around the boiler/water heater, behind the washing machine (whose hoses deserve their own respect), and under every rug you never move.

The response rule

Fix what's plainly homeowner-territory — a tap washer, a flapper, a showerhead connection are genuinely DIY jobs. Anything inside a wall, under a floor, on the supply pipe itself, or recurring after repair goes to a plumber promptly — and "promptly" is the whole point of this page: the leak's bill compounds daily, and unlike most bills on this desk, interest never stops accruing. The once-a-season checklist includes a look under the sinks for exactly this reason.

Sources: US EPA WaterSense, Fix a Leak Week facts (10,000+ gal/household/year; 3,000+ gal for a 1-drip/second faucet; meter test). Reviewed September 2026 · general information; insurance outcomes vary by policy and jurisdiction.