Private water supplies

A Private Water Supply (PWS) is any water supply that is not provided by a water company (water undertaker) and which is not considered to be a 'mains' supply.

Private water supplies can be obtained from a variety of sources including:

  • springs
  • wells
  • boreholes
  • rivers and streams
  • lakes or ponds
  • a private distribution system (mains water which is privately distributed by a second party)

The supply may serve just one property or several properties through a network of pipes. All private water supplies should be registered with your local council.

In the Arun district, we maintain the Private Water Supply Public Register.

All private water supplies can present a potential risk to health unless they are properly protected and treated. Unlike main water supplies, many private supplies are not treated to remove contamination. You may not be able to tell whether your water is safe because contamination within the water may not have a smell, taste or affect the colour of the water.

Private Water Supply (England) Regulations 2016

These regulations safeguard public health by ensuring that private water supplies are ‘wholesome’ and ‘safe’ to drink, setting quality standards similar to those of mains water supplies. The regulations cover all private supplies, although those serving a single dwelling will only be risk assessed and sampled upon request of the owner or occupier.

We will charge for this work, please see our table of charges. 

Risk Assessments

The regulations also require each supply (excluding single private domestic dwellings) to be risk assessed every five years to determine how often sampling needs to be carried out, and what should be sampled for, such as which types of bacteria or chemicals. This involves surveying the supply, from the source through to point-of-use, to identify factors that could lead to contamination. Factors influencing sampling requirements include the type of source (such as borehole, well, or private distribution system), how well it is protected, the treatment methods in place, the number of people served by the supply, and the intended use of the water.

Risk assessments will normally be carried out by prior appointment, and where possible details of what needs to be inspected and considered will be provided, prior to the site visit. This is to ensure that the owner or occupier can arrange access to the various parts of the water system, arrange for someone with detailed knowledge of the system to attend, and generally reduce the amount of time we are required to be on site.


Samples will normally be taken from a consumer tap and sent for analysis at an approved laboratory. The sampling frequency and the extent of analysis needed will depend on the results of the risk assessment.

Larger supplies (using more than 10 m³ water per day and serving 50 or more persons) and those serving commercial premises are required to undergo regular 'check monitoring', as well as more extensive 'audit monitoring' on a less frequent basis.

Small supplies (using less than 10 m³ water per day and serving less than 50 persons) are monitored at least once every five years and more frequently if shown to be necessary by the risk assessment.
Supplies serving only an individual domestic dwelling will only be risk assessed and tested at the request of the owner or occupier. However, single supplies must still register with us, so the private water supply can be placed on the public register.


Any sample that fails to meet the prescribed concentrations laid out in the regulations will be investigated to determine the reason for the failure and to identify what action is needed to improve the supply. This may mean further sampling being conducted at the source, holding tanks, and/or other parts of the infrastructure to assist the investigation.

If a wholesome supply cannot be achieved through implementing physical changes to the supply network, the water will require treatment before use. A wide range of treatment options are available.


In the event of failure, where a supply is found to be 'unwholesome' or a 'risk to human health' a notice may be served prohibiting or restricting the supply or requiring certain work to be carried out.


We charge to cover the costs of carrying out our duties under these regulations to those responsible for the supply. Where part of a shared supply is used by some commercial activity such as a bed and breakfast, the charges may be divided between the commercial and non-commercial properties proportionally. Please see a breakdown of our charges

Additional information

Commercial or large supply

The commercial or large supply 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 food chain. This category includes B&B, holiday lets, pubs, and food production premises. Also within this category are domestic private water supplies using more than 10 m³ water per day or supplying water to 50 or more persons such as large caravan sites.

Risk assessment and sampling

Risk assessments can only be performed by the local authority or by persons the local authority has deemed competent. The local authority is responsible for ensuring sampling is completed according to legislation, therefore if you would like another company to take and analyse samples of your private water supply, the local authority will need to approve the sampling company and the parameters to be analysed, prior to samples being taken. The analysis must comply with all the current legislation. The local authority will need to be sent the result certificates directly from the laboratory if a third party has been given prior approval by the local authority.

A risk assessment is needed to:

  • protect public health
  • maintain public/customer confidence in the drinking water supply
  • identify the legal duty and the responsibility of the water supplier

The risk assessment will illustrate how to minimise the potential risks to your supply and to human health and provide adequate information to allow audit monitoring parameters to be identified.

On completion of your risk assessment, we will explain how often the supply needs to be sampled, based on the risks identified. Every five years the risk assessment will be reviewed. You will receive the assessment report and a copy will be retained by us for 30 years.

The risk assessment will typically take approximately two hours. Ideally, the person responsible for the supply should be present so that the risk assessment can be conducted as quickly and efficiently as possible. During the risk assessment we will need access to the source of the supply such as the borehole, well/spring, any collection chambers, holding/storage tanks including header tanks which may be found in roof spaces, and finally the point of use of the supply.

Sampling time frame

supply sampling timeline
Supply How often sampling should take place

Single private dwelling

No requirement - sampled at the request of the owner/occupier

Small domestic supplies

Once every 5 years or more frequently if the risk assessment identified a need

Private distribution system

Dependant on need, identified by risk assessment

Large or commercial supplies

To be determined by the volume of water supplied


Reasons to register your water supply with us

So that we can:

  • carry out risk assessment and monitoring if required under the regulations
  • advise the appropriate agencies to ensure there is no risk to your supply's catchments area (for example, advising persons undertaking bio-solid spreading on land that there are private water supplies which may be affected)
  • inform you of potential contamination threats to aquifers (body of rock and/or sediment that holds groundwater) that may serve your supply
  • notify you of any updates of legislation involving private water supplies and your responsibilities

Keeping your supply safe

All parts of your supply should be routinely monitored and inspected to ensure that it is in good working order and has not been interfered with or damaged. The supply needs to be appropriately protected throughout, from source to point of use. This should include a maintenance programme to clean the distribution system and storage tanks or header tanks, and to ensure all treatment works are working as they should according to manufacturer's guidelines.

Supplying water to others

If you supply water to others with or without a charge, for example other domestic premises, renting out holiday accommodation or to commercial premises with employees or food production, it is your responsibility to ensure the water is wholesome and does not pose a risk to human health.

Getting your supply checked

Unless your supply serves a single domestic dwelling, your supply will be risk assessed and monitored by us in the next five years. However, if you suspect that something is wrong with the supply or you would like to request a sample to be taken and analysed you can contact our environmental health team to discuss your concerns and to arrange for any sampling to be carried out.

Further guidance on the Private Water Supplies (England) Regulations 2016 is available on the Drinking Water Inspectorate (DWI) website.

Contacting us

If you have an enquiry regarding private water supplies, please contact us.