Water supply

Cold water supply

The water supplied to your home must meet the standards set in the Water Supply (Water Quality) Regulations 2000. The standards are strict and the Drinking Water Inspectorate (DWI) conduct regular quality tests to maintain standards. The areas covered are:

  • Bacteria chemicals such as nitrates and pesticides
  • Metals such as lead
  • The way water looks and tastes

Here are some tips to help prevent bacterial growth and contamination of the water supply.

Hot and cold water system

If you have a domestic hot water cylinder in your home, ensure that the thermostat is set at 60ºc. Do not reduce this setting or the setting of your boiler thermostat, as bacteria can multiply at lower temperatures. If you have a combination boiler or multi-point water heater, do not reduce the hot water thermostat setting. If you are away from home for long periods, for example holidays or hospital stays, the water in your system can deteriorate if unused. When you return home, heat up your system to the normal temperature, open each tap and run for at least five minutes. Cold taps should be flushed until the water runs cold. When flushing taps and other outlets, open slowly and take care not to splash or spray water into the atmosphere. Tap spouts on your bath, basin and sink may become contaminated from external sources. Clean tap spouts by wiping with a dilute bleach solution. You can dislodge heavily scaled or contaminated taps using a nylon brush.


If you have a shower fitted with a flexible hose, make sure that a hose-retaining ring is fitted to prevent the shower head falling into your bath water. Don’t use rubber push-on shower hoses on bath taps. Clean your shower head regularly using a nylon brush then soaking in a bleach solution.

Little used taps/outlets

Over time the water in your pipework and fittings can deteriorate if a tap or appliance is not used. Open each tap and run for at least five minutes on a weekly basis to make sure your water remains fresh. Flush cold taps until the water runs cold.

Other fittings and appliances

If you have an outside tap fitted, the installation must comply with the Water Supply (Water Fittings) Regulations and incorporate a backflow prevention device - usually a double check valve. Any appliances you buy which are connected to the water supply must comply with the Water Regulations. All domestic appliances such as washing machines and dishwashers comply with the appropriate standards but many commercial appliances do not and are not suitable for home use. If you have any concerns regarding any of the above in your home, please contact us.