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Purbeck District Council private water supplies

Information on what private water supplies are and ways they are tested.

What is a private water supply?

A private water supply is one which is not provided by a water company. Approximately 1% of the population in England and Wales has a private water supply to their homes. Most private water supplies are in rural locations and are from wells, boreholes, springs or streams.

What are the implications of the Private Water Supplies Regulations 2016?

The new Private Water Supplies Regulations 2016 cover all private water supplies and private distributions systems. They came into effect in June 2016 and look to further safeguard public health by ensuring that supplies are safe to drink. The inspection and sample regime that councils have to undertake has been significantly increased.

Private water supplies are categorised into four groups:

  1. Single private dwellings.
  2. Small domestic supplies supplying fewer than 50 people.
  3. Large domestic supplies supplying over 50 people or serving commercial premises, including B&B's and holiday lets.
  4. Private distribution systems where mains water is then used to supply a number of properties, including caravan parks.

Risk assessments and sampling requirements

The regulations require the council to carry out a risk assessment of private water supplies every five years. This involves surveying the supply to identify potential contamination from the source to the consumer's tap, identifying possible prevention measures and treatment options. This will identify which parameters need to be sampled for when testing the water supply. We have five years to complete the initial risk assessments for all small and large water supplies as well as private distribution systems.

  1. Single Private Dwellings: These will not require routine monitoring or a risk assessment. However, we can sample or risk assess at owners request.
  2. Small Domestic Supplies: The amount of monitoring will depend on the outcome of the risk assessment. However, it will be a minimum of once every five years. Supplies will be sampled for basic parameters and anything else that arises from the risk assessment.
  3. Private Distribution Systems: Monitoring must be carried out according to the outcome of the risk assessment.
  4. Large Supplies or Commercial Premises: Two types of monitoring will occur on these supplies:
  • Check monitoring ensures the wholesomeness of the water; the frequency of check monitoring will depend on the amount of water used
  • Audit monitoring determines whether the water supply meets the relevant standards. The range of tests for audit monitoring is extensive and the amount of monitoring depends on the outcome of the risk assessment

Note: dairies are included in the commercial category and therefore subject to the full testing regime.

Investigation and action in an event of a failure

All quality failures must be immediately investigated to determine the cause of the failure and whether it was caused by the condition of the distribution system. We must require remedial action and will prohibit or restrict the use of water if it could be harmful to health.

The new regulations make it easier for us to take action. We will always try to resolve problems informally first. If unsuccessful, formal action must be taken.


We can serve an authorisation to allow failed supplies to continue whilst works are carried out to achieve compliance. Authorisations may only be granted for failures that do not constitute a health risk (usually chemical parameters). Before we issue one, we will consult all water users and the Health Authority and take their views into account. We will inform them of the authorisation and its conditions and provide advice to those that may be at greater risk e.g. parents of babies. We will review authorisations from time to time to ensure sufficient progress is being made towards improvement.


Notices will be served to improve, restrict or prohibit unwholesome supplies. Failure to comply with the notices may result in either works in default or prosecution in a Magistrates Court.


Appeals can be made to the Magistrates Court or the Secretary of State depending on which notice is served.

Frequently asked questions

What is a commercial/large supply?

The commercial/large category includes any business that supplies water from a private water supply to the public for drinking, washing, food preparation, or where the water is used in a way that it is likely to enter the human chain (e.g. dairies washing down equipment). This category includes B&B, holiday lets, pubs, dairies and food production premises. Also within this category are domestic private water supplies that provide water to more than 50 people.

What if the supply outlet is not on my land?

The owner of the private water supply is responsible for providing safe water to the users even if the supply outlet (tap) is not on the owners land.

Can I do the risk assessment and sampling myself?

Risk assessments can only be performed by the local authority or a company the local authority has appointed and approved to act on its behalf.

The local authority is responsible for ensuring sampling is completed according to legislation, therefore if you want another company to take and analyse samples of your private water supply, the local authority will need to approve the sampling company and analysis suite prior to samples being taken. The analysis must comply with the new legislation and the local authority will need to be sent the results certificates directly from the laboratory.

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