Grange PlumbingWhy underground leaks go unnoticed
Your supply pipe runs underground from the water company's stopcock at the boundary into your house — typically buried 750mm under the front garden or driveway. Because it's out of sight, a slow leak can run for months or even years before anyone notices. The water doesn't appear in your home — it soaks into the surrounding ground — which is exactly why these leaks are so expensive when finally caught.
1. Your water meter ticks over with everything off
This is the single most reliable test. Turn off every tap and water-using appliance in the house. Go to your external water meter (usually a small chamber on the pavement or just inside your boundary). If the small dial is still rotating, water is flowing somewhere — and if your internal stopcock is also off and the meter still ticks, the leak is on your supply pipe.
2. Unexplained jump in your water bill
Your usage hasn't changed but the bill has crept up by £20, £50 or more per month? A pinhole leak on a 25mm MDPE supply pipe can lose 50–100 litres an hour without making any visible mess at ground level. Compare your meter reading to last year — if usage is up significantly with no change in household routine, suspect a leak.
3. Damp or boggy patches in the front garden
Look at the route the supply pipe takes from the boundary to the house. In dry weather, an unusually lush, dark-green or boggy strip following that line is a classic giveaway. In winter or after rain it's harder to see, but the ground over the leak often stays soft and squelchy long after the rest dries out.
4. Drop in water pressure throughout the house
A failing supply pipe — especially old lead, galvanised or pinholed copper — restricts flow. If every tap in the house has weakened over months (not just one), and your neighbours' pressure is fine, the bottleneck is almost certainly your buried supply pipe.
5. The sound of running water with nothing on
Stand by your internal stopcock late at night with everything off and listen. A hissing, rushing or trickling sound near the stopcock often means water is escaping somewhere upstream — i.e. in the buried supply pipe between the meter and the house.
6. Subsidence or cracked drive/path slabs
A long-running leak washes fines out of the soil around it, which causes the ground above to settle. Sudden cracks in a previously flat driveway, paving slabs that have tilted, or a small dip in the lawn that follows the pipe route — these are late-stage signs the leak has been running for a while.
What to do if you suspect a leak
1) Confirm the meter test above. 2) Call your water company — most will send someone out free to check whether the leak is on their side (the communication pipe) or yours (the supply pipe). 3) If it's yours, get a fixed quote for moling rather than open-cut trenching. Moling fits a new MDPE supply pipe between two small pits without digging up the drive, garden or paving — typically completed in a single day.
How we can help
We carry out leak detection and moling across Sussex and Surrey every week. Free site visit, fixed written quote, no call-out fees. Call or WhatsApp 07894 956041.
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