Important message for supply owners and users of private water supplies

Sampling and Risk Assessing is a means of validating that the risk mitigation measures in place such as source protection, treatment, storage etc. are effective.

In line with the guidance from the Drinking Water Inspectorate and World Health Organisation, we recommend that consumers and other relevant persons of private water supplies continue their operational checks and ensure that maintenance is being carried out as required. This will include replacing UV lamps; monitoring chlorine dose; making sure there are sufficient spares of essential equipment and ensuring supplies remain wholesome at all times. Actions must be documented and available for inspection should Dorset Council have concerns that there is an ongoing risk to health.

The Drinking Water Inspectorate request that we provide the following links Drinking Water 2023 Private Water Supply Report for England and Impact and future of the regulatory model and legislative framework Surrounding Private Water Supplies in England and Wales

For further information please contact

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. The Private Water Supplies (England) Regulations 2016 and The Private Water Supplies (England) (Amendment) Regulations 2018 set out standards for the quality of the water and place a duty on the Council to sample and risk assess these supplies.

Responsibility for a private water supply

The person responsible for a private water supply is called the relevant person and is defined in the Water Industry Act 1991 as;

  • the owner or occupier of the premises supplied; and
  • the owner or occupier of the premises where the source of the supply is situated even if the source lies outside the local authority's area; and
  • any other person who exercises powers of management or control in relation to that source

There may be more than one relevant person for a supply.

The implications of the Private Water Supplies Regulations 2016 and 2018 (Amendment) Regulations

The Private Water Supplies (England) Regulations 2016 and The Private Water Supplies (England) (Amendment) Regulations 2018 cover all private water supplies and private distribution systems. They look to safeguard public health by ensuring that supplies are safe to drink by risk assessment and regular sampling. The inspection and sampling regime that we have to undertake has been significantly increased and we are entitled to recover the costs of the work involved.

Private water supplies are categorised into four groups:

  1. Single domestic dwellings: A supply serving only one owner occupied property
  2. Small supplies (Regulation 10): Supplying fewer than 50 people with water used for domestic purposes
  3. Large supplies (Regulation 9): Supplying over 50 people with water for domestic purposes or serving commercial premises including: B&Bs, holiday lets, any rented domestic properties, food production businesses, public buildings, etc.
  4. Private distribution systems (Regulation 8): Where mains water is supplied to a number of properties through a private network of pipes

Risk assessments and monitoring requirements

Risk assessment

The regulations require the council to carry out a risk assessment of Regulation 8, Regulation 9 and Regulation 10 private water supplies at least every five years. This involves surveying the supply to identify the risks (potential failures of standards and risks to human health) and to take action to control those risks. This risk assessment will also assist in identifying which additional parameters, if any, need to be sampled when testing the water supply.

Monitoring and sampling

The regulations stipulate how frequently and for which parameters each category of private water supply will be sampled:

  1. Single domestic dwellings: Unless requested by the supply owner no sampling is required
  2. Small supplies (Regulation 10): Sampling is carried out at least once every five years and samples are tested for a reduced set of parameters compared to Regulation 9 supplies. These are listed in the regulations as Group A parameters.
  3. Large / commercial (Regulation 9): Sampled at least annually (or more frequently) depending on the volume of water used or if there are concerns that warrant increased monitoring. Parameters for Regulation 9 supplies are more comprehensive and include both Group A and Group B parameters in the regulations.
  4. Private distribution systems (Regulation 8): Receive the same five-yearly Group A sampling as small supplies, unless there is a requirement for increased monitoring

Private water supplies and dairy farms

Water used for dairy farming, e.g. for cleaning storage vessels, does not fall within scope of the Private Water Supply Regulations: 'Supplies used exclusively to wash down a surface, where the water will not affect any final product intended to be consumed.' Therefore, the use of a private water supply in the dairy process will not determine a supply’s categorisation. The categorisation and consequent level of monitoring required will be determined in relation to the other uses of the water. For example, if the supply also feeds a holiday letting it will be categorised as a 'Large/Commercial' supply and require monitoring as such. For further guidance on the types of private water supply please see the Drinking Water Inspectorate’s guidance.

Fees and charges

The Regulations make provisions for local authorities to charge fees to the relevant person(s) for conducting duties under these regulations.

Some areas have their own set of charges for carrying out a risk assessment: Private Water Supply Fees and Charges

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. 

If the supply is considered to be hazardous to health due to its failure, for example, as a result of certain bacteria being present within the sample, then:

  • we will notify all users on that supply of the failure and provide advice on any action to be taken, for example, to boil all water before use;
  • we may carry out an investigation to identify the cause of the failure at a cost;
  • we will serve a notice on the person(s) responsible for the supply. This will detail the action that needs to be undertaken to restore the water quality to the required level. Failure to comply with the notice may result in prosecution. Once the water quality is at the required level, we will notify all the users of the supply to advise the water is safe to drink.

If the supply fails to meet the national drinking water standards, but the failure is not considered to be a hazard to health, for example, high levels of iron which may stain laundry but may not be considered a risk to health, then:

  • we will notify all users on that supply and provide advice on any actions that would improve the quality;
  • we may carry out an investigation to identify the cause of the failure at a cost;
  • we will work informally with the person(s) responsible for that supply to try and improve the quality of the supply


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.


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