No Cold Water Upstairs

What's happening?

In many UK homes the kitchen cold tap is fed direct from the mains, while the bathroom taps are fed from a cold water storage tank in the loft. If the upstairs has no cold water and the kitchen does, the tank is likely empty, its float valve has stuck shut, the valve feeding it has been closed, or an airlock is blocking the pipe down from the tank. After a mains cut or a drain-down, the tank can take a long time to refill or never recover. Weak flow rather than none belongs on the low water pressure upstairs page.

What usually causes it?

• A float valve on the loft tank stuck shut or worn out, so the tank never refilled
• The supply to the tank closed at a servicing valve after work, or blocked
• An airlock in the pipe from the tank to the taps
• A frozen or burst pipe between the tank and the bathroom
• A tank that has been drained for work and not refilled
• A leak on the tank or its pipes that empties it faster than it fills
• A mains outage that has not fully recovered at the tank

Is it dangerous?

Medium, because a stored hot water cylinder is often fed from the same tank. If the tank is empty and the cylinder cannot refill, turn off the immersion heater and tell your heating engineer before running the heating. A frozen tank or pipe can burst when it thaws.

Can I fix it myself?

Check with a torch whether there is water in the loft tank, and whether the float valve is lifting. Make sure the valve feeding the tank is fully open: the Water Fittings Regulations require an adjustable float valve and a servicing valve on every cistern inlet. Run the kitchen tap to confirm the mains is on. Try clearing an airlock by running the upstairs tap while another mains tap runs, or use the hose method WaterSafe describes. If the tank is full and the taps are dry, the pipe is blocked or frozen. Do not climb into a loft with no boards or no light.

When should you call a plumber?

Call a plumber when the tank is empty and will not refill, when the float valve or its servicing valve is stuck, when you suspect a frozen or leaking pipe, when an airlock will not clear, or when the hot water cylinder shares the same tank.

What will the plumber actually do?

• Inspect the loft tank, float valve, servicing valve and overflow, and refill the tank
• Replace a worn float valve and fit a servicing valve where one is missing
• Clear the airlock from the cold feed and re-test every upstairs outlet
• Find and repair a leaking or frozen pipe
• Check that the hot water cylinder and any heater refill safely, and replace a failing tank where needed

Who fixes this

• Cold water tank replacement
• Water tank repair

Questions people ask

Sources & References

1. WaterSafe: how to remove an airlock from water pipes
2. WaterSafe: why is my water pressure low
3. The Water Supply (Water Fittings) Regulations 1999, Schedule 2 (cistern inlet valves, paragraph 16)