Stopcock Won’t Turn: What to Do

Why won’t my stopcock turn?

Most stopcocks are opened once, when the house is plumbed, and then left alone for twenty years. In that time hard London water leaves scale on the spindle threads and around the gland, the brass corrodes a little, and the packing that seals the spindle dries out and grips it. The valve is still working as a pipe; it has just stopped working as a valve.

Before you do anything else, check two things. Are you turning clockwise? Some “stuck” stopcocks are already fully closed, or are being turned the wrong way. And is this definitely the main stopcock, not a valve that only looks like one? A seized valve on a washing machine branch will not stop a leak anywhere else. How to turn off a stopcock covers direction and how to confirm you have the right valve.

If there is a leak running right now

Do not spend twenty minutes wrestling a valve while a ceiling fills. Freeing a seized stopcock is a patient job, and there are faster ways to stop water in an emergency.

• Go to the outside stop valve, usually under a small cover in the pavement or path, or in the same chamber as your water meter. It turns clockwise to close. You may need a stopcock key, a long bar with a forked end, which DIY shops and merchants sell for roughly £10 to £20.
• If the leak is on a tank-fed pipe upstairs, close the gate valve on the pipe leaving the loft tank, or tie up the float arm and open the bath taps to drain the tank.
• If the leak is on a single tap, toilet or appliance, close the small isolation valve on the pipe feeding it with a flat screwdriver.
• Turn off electrics at the consumer unit if water is near sockets or fittings, but only if you can reach it without standing in water and the unit itself is dry.

The outside stop valve may also feed your neighbours if you share a supply, which is common in terraces and converted houses. Tell them before you close it. If you cannot find it, cannot open the cover, or it is seized too, you need a plumber tonight; emergency help with no water or a leak you can’t isolate explains what happens next.

How to free a stuck stopcock, in order

If nothing is leaking and you have time, work through these steps in this order. Each one uses less force than the last would, and most valves free up at step two or three.

• Grip properly. Wrap a dry cloth or rubber glove round the handle for grip and turn with both hands, clockwise, using steady pressure rather than jerks.
• Ease the gland nut. This is the small hexagonal nut just below the handle where the spindle enters the body. Loosen it anticlockwise by about half a turn with a spanner, holding the valve body steady with your other hand. That relieves the grip of the packing on the spindle. A few drops of water may appear; that is expected.
• Work it both ways. Try the handle again. If it gives even slightly, turn it back the other way a little, then forward again. Rocking it breaks the scale on the threads gradually.
• Use penetrating oil. A spray of penetrating lubricant around the spindle where it enters the gland, left for fifteen to thirty minutes, will often loosen what the first attempt did not.
• Tap, do not hit. A few light taps on the valve body with the handle of a screwdriver can crack the scale free. Keep it light: old brass is brittle.
• Once it moves, turn it fully closed and fully open two or three times to clear the threads, then tighten the gland nut back up by the half turn you loosened it.

What not to do with a seized stopcock

Each of these can turn a valve that will not move into a pipe that will not stop.

• Do not put a pipe wrench, grips or a long bar on the handle for leverage. The spindle or the crutch handle will snap, and you are left with no way to turn the valve at all.
• Do not apply heat with a blowtorch or heat gun. The joints may be soldered, the pipe may be plastic, and there is often timber or cable nearby.
• Do not strike the valve with a hammer. Brass that has lost its zinc to corrosion can crack, and the body can split under full mains pressure.
• Do not twist the whole valve. If the pipe moves with the handle, stop immediately; you are loosening the joints, not the spindle.

It turns, but the water doesn’t stop

A different fault with the same result. If the handle spins round and round without getting tighter, the spindle thread is stripped or the handle has come loose from it. If it tightens normally but the kitchen tap keeps running at a thin stream, the washer inside has worn or the seat has pitted, and the valve is passing water even when closed.

Neither can be fixed by turning harder. A passing stopcock can sometimes be rewashered, but it means isolating the supply further back first, and on an old valve replacement usually makes more sense. Our guide to replacing a stopcock sets out the options.

What the engineer does with a seized stopcock

An engineer will first isolate the supply outside the property so the stopcock can be worked on without mains pressure behind it. If the outside valve is seized or buried, a pipe-freezing kit can form an ice plug in the pipe just before the stopcock instead, which holds the water back long enough to cut the valve out.

A stopcock that has seized once will seize again, and one that only half closes is no use in an emergency. Most engineers will recommend replacing it, usually with a quarter-turn valve that is easier to operate, and adding a drain-off valve so the house can be emptied in future. The repair price is agreed with you on site before any work starts.

Call for help straight away if you have a leak and cannot shut the water off anywhere, if the handle or spindle has already snapped, or if the valve body is now weeping after your attempts. The £60 call-out covers any hour. See stopcock repair and replacement for the details of the visit.