Testing your private water supply

How we test your private water supply to make sure it is safe, what to do if your water supply fails a test or if you get an improvement notice.

Regular testing of your water supply makes sure that the water is safe. It records if the levels of bugs, chemicals and metals in your supply are above the limits set in the Regulations.

To arrange a private water supply test please contact:

Find out about:

Water testing required for your property

Testing is a requirement for most private water supplies and is recommended for all.

Private water supplies are categorised under three regulations (8, 9 and 10) and have the following associated testing requirements.

Find your supply category

Categorisation of supply and sampling frequency
Supply category Testing requirement
Regulation 10, single domestic dwelling Sampled at owners request, often when people are looking to buy or sell a property on a private water supply. We may monitor a private supply to a single domestic dwelling if we are concerned that there may be a potential danger to human health.
Regulation 10, small supply At least once every five years.
Regulation 9, large and/or commercial supply At least once a year.
Regulation 8, Further distribution supply Frequency and parameters dependent on outcome of risk assessment.

Testing process

Sampling that is undertaken to meet the requirements of the regulations can only be undertaken by the local authority or by a private contractor that has been contracted by the Local Authority.  The Local Authority cannot accept sampling results for statutory purposes from private contractors which have not been contracted by us.

Samples carried out by us are sent for processing at a UKAS accredited laboratory run by United Utilities.

The first bacteriological results are usually within 24 to 72 hours of reaching the laboratory. Full chemical samples can take up to six weeks from the date they're given to the laboratory as some of the methods are quite complex and use highly specialised equipment.

The private water team will share results with you when all tests have been completed. You will be notified as soon as possible if one of your samples fails.

Further information is available about water sample failures, including what this means and the actions required to rectify. If in doubt, contact the private water supplies team.

The Drinking Water Inspectorate is a government body that sets standards for water quality; the maximum level or acceptable range of a substance. Some are set to protect health, but others are set to prevent the water tasting, smelling or looking bad or staining laundry, sinks and baths.

Failed water tests

If a test fails and is considered a potential danger to human health, we will let you know as soon as possible.

We will advise you to either restrict or prohibit (for example boil water or do not drink the water) the use of the supply in order to minimise any potential danger to human health.

If you are a relevant person, you should let other owners or users of the supply know about the failure, and any restrictions that have been placed on it by us.

You should review all aspects of your supply from source to tap and check that all maintenance is up to date.

For example:

  • is the UV lamp switched on?
  • have your filters been changed recently?
  • is the quartz sleeve on the UV lamp clean?
  • are all tanks secure?
  • are media filters operating correctly?
  • is the source polluted?

Once you have completed any maintenance, we'll re-test the water to check the problem has been fixed.

If your water supply isn't safe, we have a legal duty to serve a notice on you to improve your supply.

We'll explain why your water failed and help you to bring your supply up to a standard that is safe for human consumption.

Improvement notices

If tests or a risk assessment show that a private water supply is a potential danger to human health by failing to meet required standards, we must serve a notice under regulation 18 of The Regulations.

You will have to comply with it. We will work with you and offer guidance to help you meet the regulatory standards and make it safe.

What the improvement notice must tell you

The notice has to include:

  • the reasons why we are sure your private water supply isn't, wasn't, or isn't likely to be safe
  • the steps we consider are needed to make sure your supply is safe
  • the time period in which the steps have to be carried out

The notice must also stop or restrict the use of the supply.

You can appeal to the magistrates’ court within 28 days of service of an improvement notice.