No Cold Water From the Tap: What to Check First
Where the cold water has stopped tells you most of the answer. If the kitchen tap still runs but the bathroom cold taps upstairs are dry, those taps are fed from a cold water tank in the loft, and the tank has almost certainly run empty, usually because its float valve has stuck or the mains feeding it has been turned down. If there is no cold water anywhere, including the kitchen, the problem is the mains supply: a stopcock turned off, a burst or frozen pipe, or work in the street. If only one tap is dry, it is that tap or the small valve under it. On a tank fed system, keep an eye on the hot water too, because the same loft tank feeds the cylinder, and if you have no hot water as well, turn the boiler and immersion heater off until the tank is refilling.
Start with the kitchen tap
In almost every UK home the kitchen cold tap comes straight off the mains, because it is the one you drink from. That makes it the best test you have.
- Kitchen cold works, bathroom cold taps upstairs are dry or trickling: the loft tank is empty or its outlet is blocked. Read on.
- Kitchen cold is dry too, and so is everything else: no mains water reaching the house. Check the stopcock, then the neighbours.
- Kitchen cold is dry but other cold taps work: that tap, its isolating valve or its cartridge.
- One tap anywhere is dry and every other tap works: that tap or the valve on the pipe under it.
No cold water upstairs: the loft tank has run dry
Many older London houses with a hot water cylinder still have a large cold water tank in the loft. It feeds the cylinder, and often the bath, basin and toilet cold supplies as well. It is topped up from the mains by a float valve, the same idea as a toilet cistern. When that float valve sticks shut, usually from scale in hard water, the tank slowly empties as you use water and does not refill. Upstairs cold taps go to a trickle, then nothing, and the toilets stop refilling.
Go up and look, carefully, with a torch. If the tank is empty or nearly so, press the float arm down gently. If water rushes in, the float valve was sticking. If nothing comes in, the mains to the tank is off or blocked: check that any valve on the pipe into the tank is open, and that the main stopcock downstairs is fully open rather than a turn or two. Our guide to the cold water tank in the loft explains what everything up there does. If it is the small tank next to it that is overfilling rather than empty, see header tank overflowing. If it is the hot taps that have stopped instead, see no water coming out of the hot tap.
Once the tank refills, the taps upstairs may splutter while air clears from the pipes. That usually settles within a few minutes of running each tap in turn. If it does not, our guide to an airlock in hot water pipes covers the cold side too.
If the loft tank is empty and it also feeds your hot water cylinder, turn off the boiler hot water and the immersion heater as a precaution until the tank has refilled and the hot taps run normally again.
No cold water anywhere in the house
Check the main stopcock first. Someone may have turned it off for a repair, or turned it most of the way off to stop a drip. It should be fully open, turned anticlockwise until it stops, then back a quarter turn. Our where is my stopcock guide shows the usual places.
If the stopcock is open, ask a neighbour or two whether they have water. If the whole street is off, it is a supply problem and your water supplier will usually list it on their website. If only your home is affected, the problem is on your side of the boundary: a burst or leaking supply pipe, a frozen pipe in cold weather, or a fault with the outside stop tap. Look for signs of water where it should not be, damp patches in the front garden, a wet floor near where the pipe comes in, or a meter spinning with everything off.
In a flat, the cold supply may come from a communal tank or booster pump rather than directly from the street. If neighbours in the block have lost water too, that is a matter for the building manager or freeholder.
In cold weather: a frozen pipe
A cold tap that stops on a frosty morning, while others work, often has a frozen section of pipe in a loft, an outside wall, under a suspended floor or in an unheated extension. Turn off the stopcock before it thaws, because a frozen pipe is often split, and the leak appears as it warms up. Thaw it gently with a hairdryer or warm cloths, working from the tap end back. Never use a flame. If you find a split, our burst pipe repair page explains what happens next.
Lagging pipes in the loft and outside walls is the cheap way to stop it happening again. Our guide to insulating hot water pipes covers the same method for cold pipes.
Only one tap has no cold water
If one tap is dry and everything else works, start with the isolating valve on the pipe under it. Someone may have closed it for a repair and not reopened it. The slot should line up with the pipe when it is open. Our guide to an isolation valve leaking explains how they work.
If the valve is open, the tap itself is the likely cause. Modern mixer taps use a ceramic cartridge that can jam with scale, and the aerator on the spout can block solid with debris, especially after work on the mains. Unscrew the aerator and try again. If water flows without it, clean it or replace it. If there is still nothing, the cartridge needs replacing.
Unvented cylinders and combi boilers
If you have an unvented cylinder or a combi boiler, there is usually no loft tank and every cold tap runs off the mains. Losing cold water then means a mains problem, not a tank problem. On some unvented installations, a few cold taps are fed from a balanced cold connection on the cylinder inlet group, so they share the pressure reducing valve with the hot water. If those cold taps and the hot water drop at the same time while the kitchen tap is fine, the inlet group or pressure reducing valve is the suspect, and that is a job for a G3 qualified engineer rather than DIY. Our guide to the pressure reducing valve explains what it does.
When to call us
Call us on 020 4652 5111 or send an enquiry if the loft tank float valve will not refill the tank, you have no cold water and the stopcock is open while the neighbours have water, or one outlet is dry and the valve and aerator are clear. A stuck float valve is usually replaced in the same visit. A supply pipe fault is traced before anything is dug up. We have 20 engineers across London, and our rate is set out on the pricing page and agreed before we attend.
Questions we get asked
- Why do I have no cold water upstairs but the kitchen tap works?
- The upstairs cold taps are fed from a cold water tank in the loft, and the tank has run dry. The float valve that refills it has usually stuck, or the mains feeding it has been turned down. Pressing the float arm down tells you which.
- How do I know if my cold taps are fed from the loft tank?
- Turn off the stopcock and run the cold taps. The kitchen tap, on the mains, stops almost at once. Taps that keep running for a while are fed from the loft tank. Weaker flow upstairs than at the kitchen tap is another sign.
- What should I do if there is no water anywhere in the house?
- Check the stopcock is fully open, then ask neighbours whether they have water. If the street is off, check your water supplier for a notice. If only you are affected, look for a leak or frozen pipe on your side of the boundary.
- Is no cold water an emergency?
- It can be if it comes with a leak, a frozen pipe or an empty tank that also feeds your hot water. In that case, turn off the heat sources and the stopcock as needed and call. A single dry tap is not urgent.
- Why does my cold tap splutter after the water comes back?
- Air got into the pipes while the supply was off. Open each tap in turn, starting with the lowest in the house, and let it run until the flow is smooth.