Yes, you can find a hidden leak at home before it shows on your water bill. Use the water meter test: turn off every tap and appliance, write down the meter reading, wait at least two hours without using any water, then read the meter again. If the reading has moved, water is escaping somewhere. A slow leak may need an overnight test to show up. A standard leak detection job costs £80 to £1,600 as a UK guide average (Checkatrade, May 2026).
Find your sign first
- Your water bill has jumped, but nothing has changed: start with the water meter test below.
- A damp patch, stain or bubbling paint: go to the room-by-room checks. The leak is often above or behind the stain.
- A musty smell, or mould growing in one spot: go to the room-by-room checks. Slow leaks feed mould long before you see water.
- You can hear dripping or running water when everything is off: go to the stop-tap test.
- Low water pressure at every tap: read the causes table, then do the meter test. A supply pipe leak can pull the pressure down.
- Your toilet keeps running, or refills by itself: do the toilet test. A leaking toilet can waste up to 400 litres a day.
- A wet patch in the garden, or one patch of grass growing much faster: the leak may be on the supply pipe outside the house.
What causes a hidden leak?
Most hidden leaks come from a small list of causes.
| Cause | What you will notice | Safe to check yourself, or plumber job |
|---|---|---|
| Worn toilet valve or flapper | Toilet refills on its own; a higher bill | Safe: the tissue test below |
| Loose or split pipe joint under a sink or bath | Damp in a cupboard; swollen chipboard | Look and feel; a plumber fixes it |
| Old copper or lead supply pipe | Low pressure; a high bill; a wet patch outside | Meter test is safe; the pipe is not |
| Leaking overflow pipe | Dripping outside pipe; a cistern that never stops filling | Look and listen; a plumber fixes it |
| Cracked waste pipe behind a wall | A damp patch after baths or showers; a smell of drains | Look only; a plumber repairs it |
| Damaged pipe under a floor | Warped boards; a warm patch on the floor; a hiss | Meter test is safe; floors are not |
| Boiler pressure relief pipe dripping | Dripping outside near the boiler; falling pressure | Look only; a heating engineer checks it |
The water meter test, step by step
This is the test WaterSafe’s guide to finding a water leak recommends. It needs two hours without water, so do it when the house is empty, or overnight.
- Turn off all water in the house. Every tap, the dishwasher, the washing machine, the shower and any outside tap. Tell everyone not to use water until the test is done.
- Wait 30 minutes. This lets tanks and cisterns finish filling, so the meter settles.
- Find your water meter and write down the reading. It is usually outside by the pavement, or under the kitchen sink. Write down all the numbers, including the red ones: black digits count cubic metres, red digits count litres. A reading of 0123 456 means 123 cubic metres and 456 litres.
- Wait at least two hours without using any water. Overnight is better, as the next section explains.
- Read the meter again. Write down the full reading, red digits included.
- Compare the two readings. If it is higher, water passed through the meter while nothing was running: you have a leak. If they match exactly, there is no leak right now, but a very slow leak may still need the overnight test.
If the cover is heavy, stuck, or full of water, do not lift it. Skip the test and call a plumber.
The overnight test for slow leaks
Short tests miss slow leaks. A drip of one litre an hour wastes 24 litres a day and over 700 litres a month.
- Take the first reading last thing at night, after the last toilet flush and the last glass of water. Write down the full reading, red digits included.
- Use no water overnight. If someone must use water, the test is void: start again the next night.
- Take the second reading first thing in the morning, before anyone uses water.
- Work out the difference. Even a small rise in the red digits means water moved overnight. A rise of 5 litres or more points to a real leak. A rise of 20 litres or more means find it straight away.
The stop-tap test: is the leak inside or outside?
Once the meter test says you have a leak, the stop-tap test finds where it is, in 30 minutes.
- Turn off the water at the internal stop tap. It is usually under the kitchen sink or in a downstairs toilet. Turn the kitchen cold tap on briefly to check the water has stopped.
- Take a meter reading. Write down the full reading, red digits included.
- Wait 30 minutes, then read the meter again.
- If the reading has risen, the leak is between the meter and the stop tap, on the supply pipe outside the house. That is the pipe you own from your boundary to the house. Read our guide to the signs of an underground water leak.
- If it has not moved, the leak is inside the house. Work through the room-by-room checks.
If the stop tap is stiff or seized, do not force it. It can snap and flood the house.
The toilet test
A leaking toilet is the most common hidden leak, and the easiest to miss, because the water runs straight down the drain. It can waste up to 400 litres a day.
- Wait until the cistern has finished filling after a flush, so the water is still.
- Place dry toilet tissue against the back of the bowl, or add food colouring to the cistern water.
- Wait 30 minutes without flushing.
- Check the tissue or the bowl water. If the tissue is wet, or the bowl water has turned the colour of the food colouring, water is leaking from the cistern into the bowl.
It is usually a worn flapper, a faulty fill valve, or a float set too high. A plumber can find it in one visit.
Room-by-room checks
Work through the house one room at a time, with a torch and a dry hand.
- Kitchen: look under the sink for damp or swollen chipboard. Check the washing machine and dishwasher hoses, and run a dry hand along each one.
- Bathroom: check the bath and shower seals, the toilet base, and the basin pipework. Check the ceiling below for stains: a stain below a bathroom almost always means a leak above it.
- Loft: check the cold water tank and pipes for drips and damp insulation. In winter, look for pipes that froze and split.
- Cellar: Check the walls and floor for damp patches, and the pipes where they come through the wall.
- Outside: check the overflow pipes, and look for a wet patch that stays wet in dry weather, or one patch of grass growing faster than the rest.
- Listen at night: when the house is quiet, listen at the wall near pipes for a faint hiss or drip.
Never cut into a wall, floor, or ceiling to chase a leak. You can hit cables as well as pipes.
No water meter? How to check without one
Not every Bradford home has a water meter. If yours does not, you can still check for a leak.
- Turn off the water at the internal stop tap, and check that no water comes out of the kitchen cold tap.
- Listen. A hiss, a knock, or running water with the stop tap off points to a leak on the supply side.
- Check the overflow pipes outside for dripping, and look for damp patches, stains, and mould inside the house.
- Watch for the signs, not the bill. If you pay by rateable value, the bill will not show a leak. Watch for damp, smells, low pressure, and running water.
- Ask Yorkshire Water. They can fit a meter so you can run the meter test, and you can report a street leak to them on their freephone Leakline, 0800 57 35 53.
What does it cost to find and fix a hidden leak?
These are UK guide averages from Checkatrade’s water leak detection cost guide (May 2026), not this business’s prices. The final cost depends on where the leak is and how hard it is to reach.
| Job | UK guide average |
|---|---|
| Standard leak detection | £80 to £1,600 |
| Repairing a leaking pipe | £220 to £440 |
| Repairing a main water service line | £330 to £1,500 |
A visible leak under a sink is found in minutes; a leak under concrete may need thermal imaging or acoustic listening. Ask whether the quote covers finding the leak only, or finding and fixing it. Also check your home insurance: many policies include trace and access cover, which pays for finding a leak.
Hidden leaks in Bradford homes
Much of Bradford’s housing is stone-built terraces and back-to-backs, many with cellars, cold lofts, and older copper or lead supply pipes, which corrode from the outside and can leak for weeks before water shows inside. Shared supplies are common, so one leak can affect more than one house.
Who pays depends on where the leak is. Yorkshire Water’s guide to whose pipe is whose sets it out: Yorkshire Water is responsible for the mains and pipes up to your property boundary, and you are responsible for the supply pipe from the boundary to your house and the plumbing inside it. Report a street leak to Yorkshire Water on 0800 57 35 53. A leak on your side is yours to repair, and Yorkshire Water may give you a leakage allowance once it is fixed, so ask them and keep the repair invoice.
For the repair itself, our water line repairs in Bradford service covers supply pipe leaks from the boundary to the house.
When to stop and call a plumber
Stop the checks and call a plumber if any of these apply:
- The meter test shows a leak you cannot find.
- Water is coming through a ceiling, a wall, or a light fitting. Turn the water off first, and switch the electricity off if water is near wiring. Do not wade through standing water.
- The leak is under a floor, behind a wall, or under concrete.
- The stop tap is seized, or the water will not turn off.
- The damp patch is growing fast, or the floor is soft underfoot.
- The leak is on the supply pipe outside the house.
- The leak is near a gas boiler. Never open the boiler casing. Gas work is for a Gas Safe registered engineer only, and if you smell gas, leave the property and call 0800 111 999.
For a hidden leak anywhere in a Bradford home, our general plumbing services in Bradford cover finding the leak and fixing it. Call Plumber Bradford Pros on 01274 041977. The sooner a hidden leak is found, the smaller the bill and the damage.
How to stop the next hidden leak
- Read your meter once a month. A slow rise shows up long before the bill does.
- Check under sinks twice a year. Look for damp and drips, and feel the washing machine and dishwasher hoses.
- Replace old flexible hoses. Washing machine and dishwasher hoses wear out. A burst hose can flood a kitchen in minutes.
- Keep the stop tap working. Turn it off and on once a year. If it is stiff, do not force it.
- Lag pipes in the loft and cellar. Frozen pipes split, and the leak shows when they thaw.
- Fix small drips straight away. A dripping tap and a running toilet are leaks too, and they waste water every day they are left.
Frequently asked questions
How do I know if I have a hidden water leak?
Do the water meter test: turn off all water, note the reading, wait two hours, then read it again. If it has moved, you have a leak.
How long should the meter test take?
At least two hours, and overnight is better. A 15-minute test only catches fast leaks.
What do the red numbers on my water meter mean?
Black digits count cubic metres, red digits count litres. Watch the red digits: a small leak moves them first.
Can a hidden leak raise my water bill a lot?
Yes. A leaking toilet can waste up to 400 litres a day, and a slow pipe leak can run for weeks before you see damp.
Who pays for a leaking supply pipe in Bradford?
Yorkshire Water is responsible for the pipes up to your property boundary. You are responsible for the supply pipe from the boundary to your house and the plumbing inside it. Report a leak outside your boundary to Yorkshire Water on 0800 57 35 53.
Plumber Bradford Pros, 164 Dyson Street, Bradford BD9 4DE. Call 01274 041977.
