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What to do if your water has been cut off

Updated: 18 Jan 2019
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If you have a combi-boiler, don't use hot water from the taps
Water tap
If your water supply fails the problem may be a burst pipe somewhere in your home or there may be a leak in the mains system. Call NIWater if you think it's a problem with the mains. For more information about burst pipes, visit our Winter Maintenance section. If you are a Housing Executive tenant you can report the problem online.

How does it affect my heating system?

Different types of heating system need looking after in different ways in the event of a water supply failure. Check what type of system you have and follow the advice below:

Any heating system with a cold water storage tank and hot water cylinder

If you have a heating system which uses a cold water storage tank (usually in the attic) and if the water supply is cut off but your cold water storage tank is full, it’s still safe to run your central heating. However you should not use your hot water. A system with a cold water storage tank may give a limited amount of hot water after the supply is cut off, but you risk running the storage tank dry. If that happens it will create an airlock when the water comes back on again, so don’t be tempted.
If your cold water storage tank has run dry, do not use your central heating or your hot water as this could cause your hot water cylinder to collapse.


If you have a combi boiler (where your hot water is heated directly from the gas boiler and you don’t have a hot water cylinder) you can use your heating but you must not use any hot water from the taps.

Economy 7

If you have Economy 7, turn the immersion heaters off. There should be two switches in your hot press.

Solid fuel central heating system

If you have a back boiler on your fire (ie if your fire heats water or radiators in your home) do not light your fire while the water is off. Once the water supply has been restored, light only a small fire at first.

Important general information

  • Don’t use your washing machine, your dishwasher or the chilled water dispenser sometimes found in American style fridge freezers.
  • We strongly recommend that you don’t use your immersion heater because you can burn it out if it’s not completely covered by water.