Private Water Supplies

In general terms, a private water supply is any water supply not provided by a water company. It is not a "mains" supply. Most private supplies are situated in the more remote, rural parts of the country. The source of the supply may be a well, borehole or spring. The supply may serve just one property or several properties through a network of pipes.

Stratford-on-Avon District Council has 223 private supplies serving over 400 properties. There are a certain number of domestic and commercial private water supplies where we routinely monitor quality both microbiologically (bacteria) and chemically (e.g. nitrates). The local authority has to decide which category the supply falls into and the risk; this tells us how often we have to test the water. Testing of supplies to a single domestic dwelling is only undertaken on request.

Safe drinking water is essential to good health. All private water supplies can pose a threat to health unless they are properly protected and treated. They may become contaminated with bacteria, protozoa, parasites and viruses (micro-organisms) or other substances. Many of these are harmless, but some may cause serious illness or even death in vulnerable people. Commercial and larger domestic water supplies are risk assessed by the authority at least every five years. This involves looking at the whole supply from source to point of use and identifying any problems that may cause the supply to become contaminated.

Many private supplies need treatment to remove contamination. This is especially true for supplies of water from a spring source, which are prone to contamination from bacteria in the environment.

Treatment Methods

Some treatment methods include:

  • sediment filters
  • ultraviolet (UV) disinfection units
  • reverse osmosis systems
  • ceramic filters
  • nitrate filters

Ultraviolet Treatment

UV treatment is by far the most common form of treatment system and, if correctly maintained, can be highly effective. Here are some tips on what to look for:

  1. If you have a UV system installed you should make sure that it is the correct size for the consumption (by asking a specialist).
  2. You should ensure that the system is serviced at least annually (UV bulbs lose their effectiveness overtime, although the bulb may still appear to be working).
  3. When bulbs are replaced, the crystal sheath inside the unit must also be cleaned. The light can be prevented from working if dirty.
  4. You should have a pre-filter (of maximum 5 micron pore size) before the filter to prevent particles from stopping effective treatment.

Notification Requirements

Property Owners

If you own a property on a private supply you should contact the local authority to ensure that we are aware of your supply. If your property serves a single property and is not let out or used for a commercial purpose, there is no requirement for the local authority to inspect or monitor the supply, but this can be undertaken on request (fee payable).


If you are a landlord of a property on a private supply you must notify us that the property is tenanted, as we will require the supply to be risk assessed and monitoring will be required (even if you are not owner of the source supply).

Commercial Premises

If you run any kind of commercial premises you should contact the local authority; some commercial activities require more frequent monitoring.

Holiday Lets

If you run a holiday let and you are on a private supply, it is still classed as a commercial activity and you should notify us as we will need to risk assess and monitor the supply.


If you rent your property and it is on a private supply, it is classified as a commercial supply and should be monitored annually. You should ask your landlord if you suspect the supply is private. You can contact us on the details below if you are concerned that you are in a tenanted property with a private supply that has not been checked.

Further Information

The Environmental Protection team liaises with water companies in our district in relation to health aspects of public water supplies. If you have problems with your mains supply or have concerns over its quality, you should contact your water company.

Further information on private water supplies can be found on the DWI website.

You can also contact the Environmental Protection team:

Last updated on 14/08/2018

Contact the Environmental Health team