Turning Off Water, Electricity and Gas in an Emergency

Which one do you shut off first?

The order depends on what is happening, not on which valve is nearest. Get it wrong and you can end up wading through water to reach a live consumer unit, or flicking a switch in a room full of gas.

• You smell gas: open doors and windows, then turn the gas off at the meter if it is easy to reach and not down in a cellar or basement. Do not touch any electrical switch, on or off. Get everyone out and call 0800 111 999 from outside
• Water is coming through a ceiling light, a socket or near the consumer unit: electricity first, if you can reach the main switch without standing in water. Then the stopcock
• Water is leaking but nowhere near anything electrical: stopcock first, then drain the pipes by opening the hot and cold taps
• The boiler is leaking, banging or smells of burning: switch it off at its own fused spur if the spur is dry, then close the stopcock if water is escaping

If the consumer unit is wet, sparking or can only be reached through standing water, do not touch it. Get out of that part of the building and call 105, the free power cut line, which puts you through to your local electricity network so they can isolate the supply from outside. If anyone is at risk of a shock, call 999.

Turning off the water: the stopcock and what it misses

The internal stopcock is a brass or chrome tap with a crutch or wheel handle on the pipe where the mains comes into the building. In most London houses it is under the kitchen sink, but it also turns up under the stairs, in a downstairs toilet, behind a panel by the front door or in a cellar. If you have never seen yours, our guide on where to find your stopcock walks through the usual hiding places.

Turn it clockwise until it stops. A stopcock that has not moved in years is often stiff, and forcing it can shear the spindle or start it leaking round the gland. Steady pressure with both hands is safer than a wrench. If it will not budge, a stopcock that won’t turn covers the options, including the outside stop tap under the small cover in the pavement or front path, which needs a long stop tap key.

The stopcock only stops mains water. In an older house with a cold tank in the loft, the pipes fed by that tank keep flowing after the stopcock is shut. Close the gate valve on the pipe leaving the tank, or run the bath cold tap until the tank empties. Heating pipes are separate again: switch the boiler off, and on a sealed system the leak slows as the pressure falls; with a small tank in the loft feeding the heating, the stopcock also stops it refilling.

Flats are the awkward case. The valve for your flat may be inside it, in a riser cupboard on the landing, or in a shared plant room, and a burst in a common pipe may need the managing agent or the building’s own contact. Stopcocks in flats explains how to tell which one is yours.

Turning off the electricity at the consumer unit

The consumer unit (the fuse box, in older wording) is usually by the front door, under the stairs, in a hall cupboard or near the meter. The main switch is the larger switch, often red or labelled "main switch" or "isolator". Push it down to off and everything on that board goes dead.

You can switch off just one circuit if you know which breaker feeds the wet area, but in an emergency it is quicker and safer to cut the lot. Before you reach for it, check your feet and hands are dry and you are not standing in water. Never reach for it with a wet hand or while touching a pipe or radiator.

Leave it off until an electrician has looked at any fitting water has reached. A ceiling rose, spotlight or socket that has had water through it can trip the power again or give a shock, and it is not safe just because it has dried out. Every modern gas boiler needs electricity to run, so expect no heating or hot water while the power is off.

Turning off the gas at the meter

The emergency control valve is a lever on the pipe going into the gas meter. The meter might be in a cupboard under the stairs, in a box on the outside wall, in a cellar, or in a meter room at the bottom of a block of flats. When the lever lines up with the pipe, the gas is on. Turn it a quarter turn so the lever sits across the pipe, at right angles, and the gas is off.

If the meter is in a cellar or basement, do not go down to it; leave the valve and get out. If your valve looks different, or you cannot tell which way is off, do not guess. If the valve is too stiff to move by hand, do not hit it or use a long bar. Leave it, get out and tell the gas emergency operator when you call.

Once the gas is off, do not turn it back on yourself. After the emergency service or a Gas Safe registered engineer has found the problem, the supply is turned back on and every appliance is checked and relit. Turning the valve back on with a hob tap or gas fire left open is how a small problem becomes a dangerous one. The full steps for a gas smell are in what to do if you smell gas.

Smell of gas: open doors and windows, and turn off the emergency control valve if it is safe to reach. Do not use light switches, doorbells, phones or anything that makes a spark inside the property. No naked flames, no smoking. Leave and call the National Gas Emergency Service on 0800 111 999 from outside.

What to check tonight, before anything goes wrong

Every one of these valves is easier to find in daylight on a calm evening than in the dark with water coming through the ceiling. Spend ten minutes on it now.

• Find the stopcock and turn it off and back on once, so you know it moves. Then open it fully and back it off a quarter turn so it does not seize open
• Clear the cupboard in front of it; a stopcock behind bleach bottles and a bin is useless at midnight
• Find the consumer unit and check the circuit labels are readable. Keep a torch that does not need mains power near it
• Find the gas meter and the emergency control valve, and make sure the lever is not blocked by boxes or shelving
• Put the numbers 0800 111 999 (gas) and 105 (power cut) in your phone
• If you rent, ask the landlord or agent where the valves are and who to call out of hours

When the valves are off: what an engineer does next

Shutting everything off buys time. It does not fix the fault, and a house with no water, no heating and no power is not somewhere you can stay for long in winter.

For a water leak, the engineer traces the source, cuts out the damaged pipe or fitting, and turns the water back on slowly so the air can escape through the taps. If the stopcock itself failed to shut off properly, it can be replaced on the same visit. For a boiler that has leaked onto its own wiring, the power stays off until the electrics are dry and checked, and anything inside the casing is gas work. Gas work is carried out by Gas Safe registered engineers.

Our 24-hour plumber service works this way at any hour. The £60 call-out gets an engineer to you, and the repair price is agreed with you on site before any work starts. If the stopcock is the problem, see stopcock repair.