The short answer
A garden patch that stays wet or unusually green when the weather is dry often points to a leaking buried water pipe. The quickest first check is a water meter test with everything switched off. If the meter keeps ticking over, the next step is non-invasive detection to pinpoint the leak before any digging.
Most gardens dry out a day or two after rain. So when one corner of the lawn stays soggy through a dry spell, or one strip of grass is greener and growing faster than everything around it, something underground is feeding it water. More often than not, that something is a small leak on a buried pipe. It can sit there quietly for months, nudging up your water bill and softening the ground, long before it ever shows as a puddle on the surface.
The good news is that you can do a fair bit of detective work yourself before you call anyone out. This guide walks through what a persistent wet patch usually means, how to rule out the innocent explanations, and how a leak is confirmed and located without tearing up your lawn.
Why a wet patch suggests a buried leak
Your supply pipe carries mains water under constant pressure from the boundary of your property to the stop tap inside, usually under the kitchen sink. If that pipe develops a crack, a loose joint or a pinhole, water escapes steadily, every hour of every day. It does not gush. It seeps into the surrounding soil and finds the easiest route, which is often back up towards the surface.
That is why the classic giveaway is a patch that defies the weather. Treated water and the constant moisture make the grass directly above thrive, so it grows quicker and looks lusher than the rest of the lawn. Buried pipes fail for ordinary reasons: ageing materials, ground movement, freezing and thawing over the winter, and tree roots that wrap around a joint and slowly work it loose. None of that is unusual, and a small leak is very fixable once you know exactly where it is.
Signs you might notice:
- A patch that stays wet or muddy through a dry, settled spell
- Grass that is noticeably greener or growing faster in one spot
- Soft, spongy or slightly sunken ground underfoot
- Water seeping between paving slabs or along a driveway edge
- A water bill that has crept up with no change in how you use water
- Weaker pressure at the taps than you remember
First, rule out the innocent explanations
Not every damp patch is a leaking pipe, and it is worth eliminating the simpler causes before you go further. A leak shows itself by being relentless, so the test is whether the wet area persists when nothing else can explain it.
Rain and drainage. Give the garden a few dry days. If the rest of the lawn has dried out and one area is still wet, rain is not the answer. Heavy clay soil and low-lying spots naturally hold water longer, and a blocked or collapsed land drain can keep an area boggy too, so consider the lie of the land.
Surface water. Check that a downpipe, gutter overflow or water butt is not quietly discharging into that part of the garden. A misdirected rainwater outlet can mimic a leak surprisingly well.
Drains and waste pipes. If the water smells or the ground stays wet near a soil pipe or inspection chamber, you may be looking at a foul drainage fault rather than a clean-water leak. The two need different approaches, so it helps to note any smell.
If none of those fit, a supply pipe leak moves up the list, and the meter test is the way to confirm it.
The water meter test
If you have a water meter, it is the simplest tool you have. The idea is to make sure no water is being used inside, then watch whether the meter still moves.
- Turn off every tap and appliance that uses water, and ask the household not to flush or run anything for the duration.
- Find your meter (often in the front garden, a footpath chamber or near the boundary), lift the lid and note the exact reading, including the small dials.
- Wait at least 30 minutes to an hour without using any water, then read it again.
If the reading has not changed, you most likely do not have a leak passing the meter. If it has crept up with everything off, water is escaping somewhere on your side, and a wet patch in the garden is a strong clue as to where.
To narrow it down further, you can turn off the internal stop tap and repeat the check. If the meter keeps moving with the inside isolated, the leak is on the buried supply pipe between the meter and the house rather than inside the property.
Who is responsible for the repair?
As a general rule across England, the buried supply pipe that runs from the boundary of your property to your inside stop tap belongs to you, so a leak on that section is usually the homeowner’s responsibility. The pipe in the street, up to the boundary, is the water company’s. In Devon that means South West Water typically looks after the mains side, while the run across your own land is down to you.
There is a grey area right at the boundary, and it is worth being aware of it. If the leak is very close to the edge of your property, it is reasonable to ask South West Water to confirm whether it sits on their pipe before you accept the cost. Many water companies also offer help towards leak repairs or supply pipe replacement in certain circumstances, so it is always worth checking what support is available with South West Water for your situation. Knowing exactly where the leak is makes that conversation far easier, which is where pinpoint detection earns its keep.
How a leak is found without digging up the garden
The old way of finding a buried leak was to dig a trench along the line of the pipe and hope. Modern detection avoids that almost entirely. A range of non-invasive methods lets an engineer confirm a leak and narrow it to a small area before a single spade goes in the ground.
Acoustic listening. Water escaping under pressure makes a faint, distinctive noise as it forces its way out of the pipe. Sensitive ground microphones pick up that sound and amplify it, and by listening at points along the pipe run an engineer can hear where it is loudest and home in on the source.
Tracer gas. A safe, non-toxic gas can be introduced into an isolated section of pipe. Being lighter than air, it rises through the soil and escapes at the leak, where a detector picks it up at the surface. It is particularly useful on plastic pipes and quieter leaks that are hard to hear.
Pressure testing and tracing. Checking how the system holds pressure confirms whether a leak is present, while pipe tracing maps the route of the buried pipe so nobody is guessing where it runs. Together these techniques turn a vague soggy patch into a precise mark on the ground, so any repair is small and targeted rather than a guess.
If your own checks point to a leak, that is the point to bring in specialist detection. Pinpointing it first protects your lawn, keeps the dig small and means the repair is done once, in the right place.
Frequently Asked Questions
Give it a few genuinely dry days. Most lawns dry out within a day or two of rain stopping. If one area stays wet, muddy or unusually green while everything around it has dried, and you cannot trace it to a downpipe or natural low spot, a buried leak becomes the likely cause and is worth investigating.
Yes. A steady trickle of clean mains water keeps the soil above the pipe constantly moist, so the grass there grows faster and looks lusher than the rest of the lawn. A bright green stripe or patch that follows a straight line is a common pointer to the route of a leaking supply pipe underneath.
No. Non-invasive methods such as acoustic listening, tracer gas and pipe tracing let an engineer pinpoint the leak to a small area first. Any excavation is then limited to that one spot, rather than digging along the whole pipe run, which protects your lawn and paving.
As a general rule the supply pipe from your boundary to your inside stop tap is the homeowner’s, while the pipe in the street is the water company’s. In Devon that is South West Water. If the leak is close to the boundary, ask them to confirm which side it falls on, and check what repair support they offer.
You can carry on using water normally, but the leak will keep wasting it and adding to your bill until it is fixed. If the wet area is worsening or affecting foundations or paving, it is sensible to arrange detection sooner rather than later so the problem can be located and repaired before it spreads.
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