Where Is the Stopcock in a Sidcup 1930s Semi?

In a 1930s semi or chalet bungalow in Sidcup, the stopcock is nearly always in one of three places: under the kitchen sink, under the floorboards just inside the front door, or in the downstairs cloakroom. Turn it clockwise to shut the water off. If it is stiff, do not force it; use the outside stop tap at the front boundary instead.

Why Sidcup houses are predictable

Sidcup, DA14 and DA15, is a 1930s town. From Blackfen and Longlands to Foots Cray, street after street was built in the same decade by builders working from similar plans. That means the water supply came in the same way in most of them: from the main in the road, through an outside stop tap near the front boundary, under the front path, and in through the front of the house.

Where it surfaced depended on where the kitchen was. In many semis the kitchen was at the back, so the pipe ran under the hall floor to reach it, and the stopcock was put either at the point it came up through the floor or at the kitchen sink.

Where should I look?

Under the kitchen sink

Clear the cupboard and look at the back and the floor of the unit for a tap on the incoming cold pipe. If the kitchen has been refitted, which in a ninety-year-old house it almost certainly has, the stopcock may be behind a removable back panel, or behind the kickboard at the bottom of the units. Shine a torch through the gap under the base units.

Under the front floorboards

Lift the hall carpet just inside the front door and look for a short board or a small trap. The stopcock may be sitting in the void just below, close to where the pipe comes through the front wall.

In the downstairs cloakroom

Many 1930s semis had a small downstairs toilet, and it is a common place for the supply to come up. Check under the basin and behind any boxing.

Garage, if it is attached

In chalet bungalows and semis with a side garage, the supply sometimes enters through the garage wall.

What is the outside stop tap?

It is a second valve, usually under a small square or round cover in the front path or the pavement near your boundary. It is the backup when the inside stopcock will not move. You need a stop tap key, a long metal tool that hardware shops sell, to reach down and turn it. If the cover is buried under gravel or a driveway, find it before you need it.

How do I shut the water off for a burst pipe?

1. Turn the stopcock clockwise until it stops, using firm hand pressure only.
2. If it will not turn, go to the outside stop tap and turn that clockwise with a stop tap key.
3. Open the cold taps in the kitchen and bathroom to drain the pipes.
4. If you have a loft tank, open the bathroom cold taps fully to drain it, because it keeps feeding the bathroom after the mains is off.
5. Switch off the immersion heater or water heater.
6. Turn off the electrics at the consumer unit for any room where water is near lights or sockets.
7. Put buckets and towels under the leak, move anything valuable, then call.

Why will my stopcock not turn?

Sidcup’s water is very hard. The Sidcup supply zone sits at around 331 mg/l on Thames Water’s figures, which is above the 300 mg/l line Thames uses for “very hard”. Scale builds up inside an old stopcock until the spindle locks. If you force it, the spindle can snap or the old pipe it is fixed to can crack, and then the stopcock you were trying to use is the leak.

The fix is to replace a seized stopcock on a calm day, ideally with a modern quarter-turn valve that is easy to operate in a panic.

What is the pipe below my stopcock made of?

Look at the pipe coming up from the floor into the stopcock. In a Sidcup semi that has never had its supply replaced, it may still be the original lead or iron. Lead is dull grey, soft (a scratch shows silver), has no screw joints, and its joints are bulbous swellings. Iron is hard, often rusty, and a magnet sticks to it. If it is either, read our guide to a lead supply pipe in a Sidcup house, because those pipes fail quietly under the front path.

What else should I check while I am there?

• Isolating valves under the kitchen sink, on the washing machine, and on the pipes to each toilet. Small screw valves you turn with a flat screwdriver let you shut off one fitting without the whole house.
• The heating. Most Sidcup semis had heating added after they were built, with pipes chased into the solid front-room floor. The stopcock does not stop a heating leak on a sealed system. If the boiler gauge keeps dropping and there is a warm patch on the floor, that is a different problem.
• The loft tank, if you have one, and whether it has its own valve on the outlet.

Need a plumber now?

If water is pouring out and the stopcock will not shut it off, Call 07868 281022. Tell us your postcode, what is leaking, and whether you have the water off yet. We cover burst pipes in Sidcup and water leaks across DA14 and DA15, including Blackfen, Longlands and Foots Cray, and we agree the price with you before any work starts. See our Sidcup page for more.