Stopcock Won't Turn

What's happening?

Your internal stop tap, also called the stopcock, is the valve that controls the water into your home. It seizes because the spindle corrodes or scale locks the washer, usually from years of not being turned. A stop tap that turns but does not shut off completely has a worn washer. The external stop tap, near the boundary under a small cover, belongs to your water company, and WaterSafe says you may need their permission to use it, even in an emergency. This page is about the valve not operating. A valve that leaks from its handle or nut is on the stopcock leaking page.

What usually causes it?

• Corrosion or scale on the spindle after years without turning
• A washer inside that has swollen or stuck to its seat
• A gland nut set too tight, binding the spindle
• A handle that has snapped or is loose on the spindle
• A valve that has been painted over or boxed in and not exercised
• A worn washer, so the valve turns but water still passes
• A plastic external stop tap that needs only a quarter turn but is jammed with debris

Is it dangerous?

It matters in an emergency: a stop tap that will not close means you cannot stop a burst. Forcing it with a long wrench or a pipe on the handle can snap the spindle or the pipe, so do not. Never heat a stop tap with a blowtorch.

Can I fix it myself?

Try gently: a small back-and-forth movement, then a little more, not a hard pull. Penetrating oil on the spindle may free it overnight. If it does not move, do not keep trying. Shut the water off another way: the Water Supply (Water Fittings) Regulations require servicing valves so parts of the system can be isolated, so look for isolating valves under sinks and by the toilet, or in the airing cupboard. WaterSafe says that if you cannot turn the water off, a plumber can help, and the external stop tap belongs to the water supplier. Tenants should tell the landlord or agent at once. Once it is free, turn it fully open, then back a quarter turn, and exercise it a couple of times a year.

When should you call a plumber?

Call a plumber when the stop tap will not turn, when it turns but does not stop the flow, when you have an active leak and cannot isolate it, when the handle has snapped, or when the outside stop tap is stuck or buried and the water company has to be involved.

What will the plumber actually do?

• Free the valve with controlled penetrating oil and the right tool, or isolate elsewhere if it will not move
• Replace the washer or headgear if the valve does not close
• Fit a new stop tap and a servicing valve beside it, draining the supply down first
• Operate the external stop tap with the key where permitted, and involve the water supplier where it is stuck
• Test the new valve and show where it is, so everyone in the house can find it

Who fixes this

• Stopcock replacement
• Water supply isolation

What it usually costs

Stopcock Replacement Cost

£100–£200

Questions people ask

Sources & References

1. WaterSafe: what to do if you can't turn off your water supply
2. WaterSafe: external stop tap not working
3. Which? Trusted Traders: what to do if your stopcock or stop tap doesn't work
4. The Water Supply (Water Fittings) Regulations 1999, Schedule 2 (stopvalves and servicing valves)