Water in your cellar: leak, drain or ground water?

A lot of Sheffield houses have cellars. In Crookes, Walkley, Hillsborough, Nether Edge and across the older parts of the city, terraces and villas were built with a cellar under the front room, often dug into the hillside. Cellars are useful, but they are also where water collects when something goes wrong. The first job is to work out where it is coming from.

The three usual sources

1. A leaking pipe. The supply pipe often comes in through the cellar’s front wall, and the stop tap and meter are often down there too. Heating pipes may run across the ceiling. A leak on any of them ends up on the floor.
2. Ground water or surface water. On a hillside, rain soaks into the ground and runs downhill. If it meets a cellar wall, it can seep through, especially after heavy or long spells of rain.
3. A drain. Old clay drains often run under or beside the cellar. A crack or failed joint can let waste water seep in, and a blockage can push it back up a cellar floor drain.

Step 1: the meter test

If you have a water meter, this is the quickest test:

1. Turn off every tap, and check toilets, the washing machine and dishwasher are not filling.
2. Read the meter and note the number.
3. Wait an hour without using any water.
4. Read it again.

If the meter has moved, water is escaping from your supply. If your meter is inside the cellar, the leak is after it, in the house plumbing. If your meter is outside in the pavement, the leak could be on your supply pipe under the front yard and seeping into the cellar.

If the meter has not moved, it is unlikely to be a mains water leak. Look at ground water, drains or the heating.

Step 2: check the heating

A heating leak does not show on the water meter. If your boiler keeps losing pressure, and the cellar water is clean, suspect a heating pipe. Our post on boiler losing pressure explains the signs.

Step 3: look at timing and smell

What you notice	Most likely source
Meter moves with all taps off	Supply pipe or plumbing leak
Clean water, appears after rain, meter still	Ground or surface water
Water near the front wall where the pipe enters	Supply pipe leak, or water tracking along the pipe from outside
Smells of sewage, or appears when drains are used	Drain leak or blockage
Boiler losing pressure, clean water	Heating leak
Water on the ceiling of the cellar	Leak from the room above

Supply pipe leaks at the cellar wall

The front wall is where most supply pipe leaks show in a terrace cellar. The pipe comes in from the street, sometimes old lead, sometimes early plastic. Joints at the wall, at the stop tap and at the meter are common leak points.

Yorkshire Water’s pipework guidance says the homeowner is responsible for the supply pipe from the property boundary to the house, and for stop taps on the property. If the pipe is shared with neighbours, the owners are jointly responsible.

If the leak is between the boundary and the cellar wall, the plumber may need to dig at the boundary to test which side the leak is on. Our post on who fixes a water leak explains that process.

Crookes: cellars on a ridge

Crookes sits high on a ridge, and its terraces are stepped along and down the slopes. Rain falling on the hill soaks down through the ground towards the valleys. Cellars dug into that slope can take on ground water after heavy rain, even when every pipe is sound. The Fulwood supply zone that serves Crookes has very soft water, 9.5 mg/l calcium in Yorkshire Water’s 2025 report, so old copper in damp cellars can also pinhole over time. Our Crookes area page has more on homes there.

If it is a drain

If the water smells, or appears when you run baths or flush toilets, a drain is likely. Keep away from the water, wash your hands after any contact, and lift the nearest manhole if it is safe to check whether it is full. If neighbours have the same problem, it may be a shared drain for Yorkshire Water to deal with. If it is your own drain, a camera survey can show the crack or failed joint.

If it is ground water

Ground water is a damp proofing and drainage problem, not a plumbing fault. Options include improving drainage outside, tanking or membrane systems inside, and a sump and pump. A specialist in basement waterproofing is the right person. A plumber can still help with the pump and its discharge.

Protecting what is in the cellar

If your boiler, electrics or a washing machine are in the cellar, think about raising them or moving them if water keeps getting in. After any water reaches a gas boiler, it must be checked by a Gas Safe registered engineer before use.

When to call

Call a plumber if the meter test shows a leak, the boiler is losing pressure or water is coming from a pipe. Our leak detection page explains how we find it without lifting more than we need to.

Send us a photo of where the water is and tell us whether the meter moves, and we will tell you which way we think it points.