Short answer: Yes, it can, although it is not the most common cause. The Association of British Insurers lists leaking drains and water pipes among the causes of subsidence, because escaping water can soften or wash away the soil under foundations. Sandy and gravelly soils are the most vulnerable. Drying clay soils and trees are the more common causes.
Can a water leak cause subsidence? The short answer is yes, sometimes. The fuller answer matters, because most cracks aren’t subsidence and most subsidence isn’t caused by leaks.
What causes subsidence
The Association of British Insurers lists four causes:
| Cause | How it works |
|---|---|
| Soil type | Clay soils shrink, crack and shift in hot, dry weather |
| Trees and shrubs | On clay, roots draw moisture out of the soil near foundations |
| Local mining activity | Old mines, quarries and pits can become unstable if the fill collapses |
| Leaking drains and waterways | Escaping water can wash away or soften soil; sandy and gravelly soils are the most vulnerable |
The ABI notes that subsidence usually happens when the ground loses moisture: dry spells and trees on clay. Leaks are one cause among several, not the most common.
How a leak can lead to movement
A supply pipe carries water under pressure all day. If it leaks for months under a house or close to its foundations, the water goes into the ground around it. In sandy or gravelly ground that water can carry soil away. In other ground it can soften it. Either way, the foundations lose some support. The ABI’s prevention advice includes keeping “gutters, pipes, and plumbing” well maintained to avoid leaks.
Cracks and a rising water bill?
Rule out the leak first: located and fixed, with a report for your insurer.
Telling subsidence cracks from ordinary ones
The ABI says subsidence cracks tend to be:
- diagonal, and wider at the top than the bottom;
- thicker than a 10p coin;
- around doors and windows;
- sudden, often after long dry spells.
Other signs are doors and windows that start sticking, and wallpaper rippling where there is no damp. Most cracks aren’t subsidence, though. New homes settle, fresh plaster shrinks, and buildings move with temperature. Cracks that are uniform and narrow, hairline to about 3mm, are usually routine.
What to do first
- Check the meter. Everything off, internal stop tap closed, and watch it. If it moves, there is a leak on the supply pipe. See how to find a water leak underground.
- Call your insurer about the cracks. Subsidence is assessed by a surveyor, not a leak detection company.
- Get the leak located and fixed if the meter shows one. It removes one possible cause, and the report is useful evidence. See underground water leak detection.
- Keep records: photos of the cracks with dates, meter readings and the repair invoice.
Bottom line
A leak can contribute to subsidence, but cracks have many causes. If you see new cracks and a rising water bill, rule out the leak first, and call your insurer about the cracks. A structural surveyor decides whether it is subsidence. Call 0115 839 0791, 9am–7pm, 7 days.