Private Water Supplies in Scotland: Rules, Councils and Connecting to the Mains

Around 3% of Scotland's population gets its drinking water from a private water supply, one that is not owned or operated by Scottish Water¹. Most of these supplies are in remote and rural areas and draw from sources like lochs, streams or boreholes¹. If your home is one of them, the law is clear about who stands behind the water that comes out of your tap: you do. It is your responsibility to manage your supply and keep it safe, and your local authority is there to advise you, assess the risk and sample the water².

That responsibility is real rather than theoretical. The quality of private water supplies in Scotland is variable: some are very good, with adequate treatment and good management, while others present a risk to health because of the quality of the water³. Outbreaks of disease attributed to private water supplies have occurred in Scotland³, and waterborne infections such as Campylobacter, E.coli O157, Cryptosporidium and Giardia can produce acute gastrointestinal symptoms including sickness and diarrhoea⁴. The hardest part for a household is that contaminated water may smell, taste and look completely normal, so you may not be able to tell whether your water is safe⁵.

This page sets out how the system works in Scotland: who is responsible for what, how to register your supply, which rules apply to you, what testing involves and costs, what treatment should do, what to do when a sample fails, why supplies run dry or freeze, and what grants and mains connection options exist. For the wider UK picture on duties and testing, see private water supply regulations; for treatment options in detail, see treating a private water supply.

Who is responsible: your supply, your council and Scottish Water

In Scotland, a private water supply is defined as any water supply that is not provided by Scottish Water¹⁰. That single definition splits the country into two worlds. On the public side, 97% of homes receive drinking water from Scottish Water, water that has been treated to make it safe and has to meet stringent regulations⁶. Scottish Water is responsible for the public supply and distribution, and for the pipes that lead up to your property boundary, including the communication pipe in the street; it will fix bursts in those pipes⁶.

On the private side, the responsibility lies with the users of the supply, or any third party who provides or manages it by contract¹². Treatment of private water supplies is usually the responsibility of the owner of the supply or property¹³. There is no water company standing behind your tap water: if the source becomes contaminated, the pump fails or the filter blocks, it is for the owner and users to deal with, with the council's environmental health team available for advice².

The division of labour between the bodies is worth knowing:

The Scottish Government provides advice and information for owners and users of private water supplies through its information site mygov.scot, including how to get your supply tested, the charges for testing, and the grant that can help improve it¹⁷. If you have a query or would like advice about managing your supply, talk to your local authority¹⁷. If your supply is cut off or contaminated during flooding, NHS inform advises contacting Scottish Water for public supplies, or your local authority if you use a private supply¹⁸.

Registering your supply with the council

All private water supplies must be registered with the council⁸. This is not optional and it is not a formality: the register is what allows the council to contact you when there is a problem in your area, to carry out its risk assessment and sampling duties, and, in a drought, to know where help is needed. Users of private supplies are required by law to register them with their local authority¹⁹.

Councils keep these registers continually updated, and the register may be shared with other public bodies such as the Scottish Environment Protection Agency (SEPA)⁸. The scale varies enormously by area: Argyll and Bute alone has approximately 3,500 private water supplies serving over 8,000 inhabitants, and many more visitors⁸.

To register, contact the environmental health team at your council. Two examples of how councils take these enquiries:

• Scottish Borders Council: telephone 0300 100 1800, or write to Council Headquarters, Newtown St. Boswells, Melrose, TD6 0SA⁵
• Argyll and Bute Council: telephone 01546 605519, or email envhealth@argyll-bute.gov.uk outlining your private water supply situation²⁰

Contact details for every Scottish council's environmental health department can be found on the CoSLA website²¹. If you are unsure whether your property is on a private supply at all, there are tell-tale signs: the property being in a remote location, since most but not all private supplies are in areas the public mains do not reach, and a lack of chlorine smell, since the mains supply usually has a faint chlorine or bleach-like odour while most private supplies are not chlorinated¹³.

One point on maps: the DWQR no longer displays a map of private water supply locations on its website because it is unable to verify the accuracy of the data³. There is no reliable national map to check; the council register is the authoritative record.

Regulated and exempt supplies: which rules apply to you

There are two types of private water supply in Scotland, and the legislation relating to each is different¹⁰. Which type you have determines whether the council must sample your water, how often, and what you must do as an owner.

The commercial category is broader than many owners expect. It includes all holiday letting premises and self-catering units and caravans, food premises, workplaces and domestic residential lets⁸. Highland Council gives similar examples: food businesses, holiday accommodation, visitor attractions, campsites, workplaces and rented homes²². If you let your property, even occasionally, your supply is almost certainly a Regulated supply.

That brings two legal duties. Commercial properties on a supply, including self-catering accommodation, must legally have a formal risk assessment carried out and are subject to routine sampling, with all supplies serving a commercial premise sampled at least annually¹³. And if you have a commercial premises served by a private supply in Scotland, you are required by law to display a Drinking Water Poster to notify all users⁸.

For purely domestic supplies, the rules are lighter but not absent. Any private water supply used for domestic purposes that supplies two or more dwellings or other properties must be risk assessed every 5 years and regularly tested in accordance with the regulatory requirements by the local authority²³. A supply serving only one owner-occupied domestic property sits at the lightest end: councils may not sample it unless a problem is suspected or you ask them to⁴. Many more people encounter private supplies only as visitors, when they stay in holiday accommodation in the more remote parts of Scotland¹⁰; if that is you, see staying somewhere with a private water supply.

Contaminated water can look, smell and taste normal

The single most important thing to understand about private supply safety is that you cannot judge it with your senses. You may not be able to tell whether your water is safe, as contaminated water may smell, taste and look normal⁵. Scottish Borders Council gives the same warning⁹.

Contamination comes from several directions. It can be bacteriological, from faecal matter such as human sewerage or animal droppings; or chemical, from fertiliser or pesticide run-off from fields, from deterioration of distribution pipework (lead, copper, nickel or zinc), or from natural sources in soils and rocks such as iron, manganese and arsenic⁸. Waterborne infections such as Campylobacter, E.coli O157, Cryptosporidium and Giardia can produce acute gastrointestinal symptoms, including sickness and diarrhoea⁴.

Because you cannot see the problem, the practical habits are:

• Watch for changes in colour, smell, taste or clarity, and treat any change as a reason to test²⁴
• Check water levels and flow rates, and monitor pumps, treatment systems and storage tanks²⁴
• Watch for unusual changes in water pressure, which can point to leaks or a failing source²⁴
• Remember that a lack of chlorine smell is normal for most private supplies, not a sign of purity¹³

For contrast, on the public supply a slight taste or smell, particularly of chlorine, is normal and no cause for worry; Scottish Water advises contacting it immediately only if you notice a particularly bad or strong smell or taste that means you cannot drink the water, or a smell or taste for the first time²⁵. If you are at all concerned about the quality of a public supply, contact Scottish Water in the first instance; if the supply is a private one, speak to the environmental health section of your local authority¹⁴.

Lead deserves a special mention because it is invisible and it comes from the pipes, not the source. If you have reason to believe lead is present in your supply, you can contact Scottish Water and ask it to take a sample from your property and tell you the results¹¹. If high lead levels are found, you will be contacted, steps will be taken to reduce exposure, and you may be advised not to drink tap water temporarily²¹. NHS inform notes that contact details for your local council environmental health department can be found on the CoSLA website if you have a private supply²¹.

Testing your water: what it costs and how long results take

Water sampling is carried out to determine the presence of bacterial or chemical contaminants which may have adverse health implications, which may affect the efficiency of any treatment installed, or the aesthetics of the water⁴. Testing checks for bacteria, chemicals and metals¹⁰.

How the process works depends on your supply type:

• Regulated (Type A) supplies are routinely sampled as part of the council's statutory sampling programme⁴.
• Supplies serving the public or a commercial operation are assessed and sampled at least once a year as a legal duty⁴.
• Small domestic supplies may not have been sampled, and there are currently no plans to sample them unless a problem is suspected or sampling is requested⁴. You can ask your council to test.

There is a charge for testing, paid at the time of your request⁴. For small domestic supplies, a fee is charged to cover sample and analysis costs⁴. The Scottish Government's mygov.scot site sets out how to get your supply tested, the charges for this, and the private water supply grant that can help improve your supply¹⁷.

Results take different times depending on what is being looked for. The first bacteriological results are normally known within 72 hours of the sample reaching the laboratory; full chemical samples can take up to 6 weeks from the date of submission to the Public Analyst⁴.

One caution from a published case study: a single, one-off water sample does not adequately assure a safe, sufficient and reliable drinking water supply, even when the results are compliant with the regulatory standards on that occasion²². Regular sampling, matched to a risk assessment of the source, is what protects a household.

If you are buying a property served by a private supply, ask about the sampling history and the risk assessment before you commit: supplies serving two or more dwellings must be risk assessed every 5 years and regularly tested²³. The council can also carry out a risk assessment of the supply and produce a report of Approved Improvement Works, which is the document you will need if you apply for an improvement grant⁴.

Treatment that protects the whole house

To ensure the water supply is safe for human consumption, councils expect that a suitable treatment system will be installed and maintained on all water supplies¹³. The key design rule is that any treatment should be point of entry, designed to treat all of the water entering the property, not point of use on a single tap⁹. The reason is simple: all water used on the premises must be safe for drinking and hygiene purposes, such as showering and tooth brushing²⁰.

Treatment works in two stages: protecting the source in the first place, and secondary treatment such as filtration and disinfection²⁴. In Argyll and Bute, the most common treatment method is pre-filtered ultraviolet disinfection¹³. A published case study of a supply serving 34 domestic dwellings used UV treatment and pH correction before the water was distributed to the properties²³.

Two warnings from the councils that run these systems. First, an untreated supply is expected to fail bacteriologically numerous times throughout the year, especially if the supply comes from or is affected by surface waters⁴. Second, even having treatment, such as filters, ultraviolet disinfection or chlorination, is no guarantee of safe water unless the treatment is adequately designed to cope with the raw water quality and the flow rate, and systems must be carefully and regularly maintained according to the manufacturer's instructions⁴. Chemical failures matter here too: failure of certain chemical or aesthetic parameters may pose a risk to human health and may also affect the efficiency of any treatment system in place, particularly UV disinfection or chlorination⁴.

For the practical side of choosing and maintaining filters, UV units and source protection, see treating a private water supply.

When a sample fails: boiling water and telling users

If your water fails a test, you will be told what went wrong, you may need to boil water or stop using it, you will get advice on how to fix the issue, and you may receive a legal notice requiring improvements¹⁰.

For most bacteriological issues, boiling of water prior to use is required: for consumption such as drinking, ice making and washing of foods, and for personal hygiene purposes such as tooth brushing⁴. Boil advice is not just informal guidance in serious cases. In one case study, the owner of a supply issued boil water advice to all the properties and commenced an investigation, and the local authority then formalised the boil water advice in a Regulation 18 Notice²³. In another, after faecal contamination of a supply, the local authority served a Regulation 18 Notice which instructed users of the supply to boil water before consumption²³.

If you are responsible for other properties or users, such as tenants, holiday visitors, customers or staff, you must:

1. Inform users about the sample failure or failures⁴
2. Notify in writing all consumers of the water at the properties that you are responsible for⁹
3. Ensure temporary measures, such as boil advice, are put into action until the cause has been investigated and rectified⁴
4. Request a further sample to confirm the remedial works have been successful⁴

Councils also have formal enforcement powers. Section 80 of the Water Industry Act 1991 gives local authorities discretionary powers to serve a notice on one or more relevant persons when a private supply is failing, has failed or is likely to fail to provide a sufficient supply of wholesome water²⁴. In practice, most cases are resolved through advice and voluntary improvements before that stage.

Dry spells, freezing and other reasons a supply fails

Private supplies fail for reasons beyond contamination, and the causes cluster around weather and equipment. Supplies can be lost during periods of drought or severe cold weather, when the source dries up or freezes, but also through undetected leaks, pipe bursts, mechanical failures such as pump failures or blocked filters, and users being permanently disconnected by a person who has control of the supply²⁰.

Prolonged dry weather brings its own sequence of problems: reduced water levels in springs, wells, boreholes and streams, lower water pressure and reduced flow rates, complete loss of supply in some cases, and changes in water quality due to lower water volumes²⁴. There is a further trap at the end of a dry spell: dry spells often end with heavy rain that causes run-off into abstraction areas, which can bring high levels of sediment and contamination to tanks and affect treatment²⁰.

What to do, in order:

1. Contact your local authority if you are having supply issues due to the effects of dry weather¹⁶. This is the first and correct call for a private supply.
2. Report the impact to SEPA as well. By reporting the impact of dry weather on your supply to SEPA, you help it better assess water scarcity stress in your area¹⁶.
3. Ask about bottled water. If issues occur in a period of Water Scarcity declared by the Scottish Government, some councils may be able to arrange for you to collect a limited supply of bottled water from one of their offices, without charge¹⁵.
4. Check for the other causes. Before assuming drought, rule out undetected leaks, pipe bursts and pump failures, which are all common causes of loss of supply¹².

For the fuller picture on managing a supply that runs low, see when a private water supply runs low or dry. Scottish Water reports the raw water available in storage reservoirs and rivers across the country on a weekly basis, which gives a picture of how dry the wider system is¹⁶.

Grants and connecting to the mains

The Scottish Government provides funding to local councils to deliver the private water supply grant scheme, offering up to £800 to eligible persons improving their existing private water supply¹. The grant is non-means tested, at up to £800 per property⁹, and is administered by local authorities on behalf of the Scottish Government¹⁷. Argyll and Bute describes it as non-means tested grant funding of up to £800 per property that may be available to improve your private water supply⁹.

Two limits on the grant matter before you plan any work:

• Grants cannot be issued retrospectively for works that are already started or completed⁹
• Grants cannot be used to allow users to connect to the public mains water supply⁹

So apply before you begin improvement works, and use the grant for treatment, source protection, storage or pipework on the private supply itself. The council's risk assessment and its report of Approved Improvement Works is the natural starting point for an application⁴. For the detail on eligibility and what the grant covers, see the private water supply grant in Scotland.

On connecting to the mains, the position has recently changed. The Scottish Government ran a private water supply connections pilot project, delivered with Scottish Water, Consumer Scotland and local councils, to improve Scotland's resilience to water scarcity, to better understand the challenges of extending the public water network to communities with private supplies, and to learn lessons for future climate change projects¹. It was a Scotland-wide scheme in which councils nominated affected communities, and it helped eligible communities affected by water scarcity explore opportunities for connection¹.

The pilot scheme has now ended, and no further communities are being considered for connection through this project¹. If you missed the pilot, the practical routes are: improving your own supply with the grant, and speaking to your council about your situation, since councils remain the delivery body for private water supply policy in their areas¹.

Where to get help

• Your council's environmental health team: the first contact for registering a supply, advice on managing it, risk assessments, sampling, and dry weather problems². Scottish Borders Council: 0300 100 1800⁵. Argyll and Bute Council: 01546 605519 or envhealth@argyll-bute.gov.uk²⁰.
• The DWQR: guidance for owners and users of private water supplies, and oversight of drinking water safety in Scotland³.
• mygov.scot: the Scottish Government's information on testing, charges and the improvement grant¹⁷.
• SEPA: report the impact of dry weather on your supply, to help it assess water scarcity¹⁶.
• Scottish Water: for anything to do with the public supply, contact it online in the first instance or call 0845 601 8855⁹. Its website also lets customers see the status of the supply in their area and report problems⁵. If you have problems with the water in your home, such as supply or quality issues, problems with pipes or sewers, blocked or flooded sewers, or sewerage flooding or pollution, the Scottish Water website has information on what to do and who to contact⁵.
• Your GP: if you think your water supply may be affecting your health, contact your GP, who can provide containers for a stool sample, and contact the council water team, who can arrange to take a sample if appropriate⁴.

For storing water at home as a buffer against supply failures, see water in an emergency, and for the wider context of household self-reliance, see self-reliance at home.