Two questions sort out almost every case in under five minutes: which taps are dry, and is anyone else in the street affected. Answer those before you touch a valve or ring a plumber, because the answer decides who fixes it and who pays.
Step one: which taps have stopped?
Go to the kitchen and open the cold tap. In most UK homes that is the one tap fed straight off the incoming main, so it tells you whether water is reaching the building at all.
| What you find | What it usually means |
|---|---|
| Kitchen cold tap dry, and every other tap dry | Nothing is getting into the building. Street outage, a closed stop valve, a frozen supply, or a burst on the supply pipe. |
| Kitchen cold tap runs, bathroom taps and toilet cistern dry | You have a cold water tank in the loft and it is empty. The mains is fine; the tank is not refilling. |
| Cold runs everywhere, no hot water | Not a supply problem. It is the boiler, the cylinder or its controls. |
| One tap dead, the rest fine | A local fault on that tap: an isolation valve closed under the basin, a blocked aerator or cartridge, or a frozen length of pipe on an outside wall. |
| Water comes, but as a dribble | A low pressure or low flow problem, which has a different set of causes. See low water pressure and when it means a leak. |
Step two: is it just you?
Knock next door or message the building group. If the neighbours are dry as well, the problem is almost certainly on the water company's network: a burst main, planned work, or a pressure fault in the area. Thames Water's own guidance runs the same way, and they publish live incidents and planned work by postcode on their network updates page. Check it before you do anything else, because it often gives an expected restoration time.
If there is no notice and the whole street is off, report it. It is their main and their repair. You do not need a plumber, and paying one to attend will not bring the water back any sooner.
What you are owed if the company is slow
Supply interruptions are covered by the Guaranteed Standards Scheme. CCW, the water consumer body, sets out the position in England: for planned work the company must give at least 48 hours' written notice, and it must restore supply by the time it stated, or within 12 hours of an emergency such as a burst main. If it fails, you are due £50, plus £50 for each further full 12-hour period, capped at twice your annual water charges, and in England these payments are made automatically. Keep a note of when the water went off and when it came back in case you need to chase it.
If only your property is affected: the causes, in the order to check them
1. The internal stop valve has been closed
More common than it sounds. A previous plumber, a builder, a new tenant testing it, or someone who knocked it while clearing out the cupboard. Find it (under the kitchen sink is the first place to look; our guide to finding your stopcock covers the rest) and gently turn it anti-clockwise until it stops. Do not force it. If it spins freely and nothing happens, that is the next cause.
2. The stop valve has failed shut
Older brass stopcocks have a loose washer assembly, often called a jumper, that lifts off the seat when the valve opens. When it corrodes or the washer detaches, it can drop back and block the flow even with the handle fully open. The symptom is a valve that turns normally but delivers little or nothing, often straight after someone has turned it off and on again. The fix is a new valve, which means isolating at the outside stop valve first. It is a short job, and not one to improvise with the supply live.
3. Something has frozen
If the temperature has been below freezing overnight, look at where the supply comes into the house and at any pipe running through an unheated space: a garage, a loft, under a suspended floor, or boxed in against an outside wall. A frozen pipe often has a light frost on it and is noticeably colder than the pipe either side. Thaw it slowly from the tap end with warm towels or a hot water bottle, never a flame, and check the whole run before the water returns in force. Our guide to thawing frozen pipes covers where London pipes actually freeze and why the split usually shows on the thaw.
4. The loft tank is empty
If the kitchen cold tap runs but the bathroom does not, go up to the loft. A cold water storage tank is refilled by a float-operated valve on the mains. If that valve has stuck shut with scale, which is common in hard-water London, the tank drains down as you use it and never refills. Lift the lid: an empty or near-empty tank with the float sitting low confirms it. A stuck valve is sometimes freed by gently moving the float arm, but a scaled valve usually needs replacing.
The reverse fault is worth knowing because the two are linked. A valve that sticks open overfills the tank and runs out of the overflow pipe instead. If you have had a dripping overflow outside recently, see loft tank overflowing, because the same valve is failing.
5. Air in the pipes after work
If the water has just been off, for work in the street, a meter installation or a repair of your own, you may get spluttering taps and then nothing from one or two outlets. That is trapped air, usually on tank-fed or hot water pipework, and it clears. If it keeps coming back, it is a different problem; airlock or leak explains how to tell.
6. A leak on the supply pipe you own
This is the one that costs money if it is missed. The supply pipe runs from the outside stop valve at your boundary into the house, and Thames Water are clear that it is the property owner's responsibility. A pipe that has split or pulled apart underground can lose so much water that little or none arrives at the taps.
The signs that point here rather than anywhere else:
- Neighbours have normal water, your stop valve is open, and nothing is frozen.
- Your water meter is turning, sometimes quickly, with every tap in the house closed. Our page on a meter turning with everything off shows how to read it.
- Wet or soft ground, a sunken patch, or water running where the pipe comes up the front path or through the front wall.
- The loss came on suddenly, often after a cold snap or nearby digging.
If that is the pattern, close the outside stop valve if you can reach it, and get the pipe repaired. Water leaking from your own supply pipe is also water you will be billed for on a meter, and Thames Water can require the repair once they are aware of it. Who owns which length is set out in water leak outside the house: who is responsible.