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After heavy rain or flooding? Rain can wash bacteria into wells, springs and boreholes. A quick E. coli retest tells you where you stand. Retest for E. coli →Home › Private water supplies Wells · Boreholes · Springs

Private water supplies: the UK guide to testing wells, boreholes and springs

If your water doesn't come from a water company, you are responsible for it. In the words of Scotland's regulator, “It is your responsibility to manage your supply and keep it safe.” Quality changes too: the DWI says it “may vary with seasonal changes to the source water”. We suggest testing at least once a year, and again after heavy rain or any work on the supply.

DWQRDWI Last checked 28 Sep 2026 Get the Complete Kit · £45
  • Quotes from UK regulators, linked
  • Home screens for E. coli, lead and arsenic
  • Clear about what needs a lab

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Three ways to check a private supply

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Complete Drinking Water Test Kit

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1 × E. coli 1 × lead 1 × arsenic 5 × chlorine 5 × fluoride

E. coli, lead and arsenic, plus chlorine and fluoride.

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Lead, E. coli and Arsenic Test Kit

The three safety checks for a private supply, for your yearly screen.

E. coli · lead · arsenic £35 View kit

E. coli Test

The quick retest after heavy rain, flooding, or work on the supply.

E. coli £15.95 View kit What a home screen doesn't cover: nitrate, pH, iron, manganese and enterococci need a lab. Your council can arrange testing.

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Start from where you are

Pick the card that sounds like you. Each one takes you to the right test or the right part of this guide.

Just moved in Start with a full screen, and ask for any past test results and maintenance records. Complete Kit → COMMON After heavy rain or flooding Rain can wash bacteria into a source. Retest for E. coli. E. coli Test → After UV or filter work Any work on the supply can let bacteria in. Retest before relying on it. E. coli Test → Taste, smell or colour changed A change is a sign something is different. Find out what the change could mean. Taste and smell guide →

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Your testing plan in a minute

Start with the supply’s postcode, then tell us where the water comes from and who uses it. You get what to test and when, the kit that fits, and what the rules say for your supply.

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01

What counts as a private supply

The Drinking Water Inspectorate (DWI) puts it simply: “a private water supply is any supply that is not provided by a water company.” DWI It may come from a borehole, well, spring, stream or lake, and it may serve one home, several homes, a farm, a holiday let or a business.

Private supplies are more common in some parts of the UK than others. Scotland's regulator says “Approximately 3% of the Scottish population uses a private water supply for drinking water.” DWQR In Northern Ireland, “less than one per cent of water comes from private water supplies.” DAERA

“It is your responsibility to manage your supply and keep it safe.”
Drinking Water Quality Regulator for Scotland DWQR

The same idea runs through the rules in every nation: the person who owns or runs the supply is responsible for it. The council is the regulator, and it has more duties where a supply is shared, let or used by a business. Chapter 05 sets out what applies where you live.

02

Source to tap: where things go wrong

Problems can start anywhere between the ground and your glass. Tap a number on the diagram at the top of the page, or read the four points below.

1 The source The DWI says “Wells and springs although derived from groundwater, are very often influenced by surface water, and are considered surface water for the purposes of water quality risks.” DWI Test: E. coli. Nitrate needs a lab. 2 Treatment UV lamps and filters only work if they are looked after: “Replace filters, lamps and/or filter media according to manufacturer’s instructions.” DWI Test: E. coli after any work. 3 Storage and pipes Tanks collect sediment and old pipes can be lead. The DWI's list of measures includes “Replace lead pipework.” DWI Test: lead and E. coli. 4 The tap Mains water is “often conditioned with phosphate to reduce the amount of lead dissolving” DWI, but on a private supply that “is highly unlikely to be equipped in private water supply networks” DWI. Test: lead, at the kitchen tap. Check all four at once. The Complete Kit screens for E. coli, lead and arsenic, plus chlorine and fluoride. View the Complete Kit
03

What to test, and what needs a lab

No single test covers everything. This table shows what matters on a private supply, which parts you can screen at home with our kits, and which need a laboratory. We would rather tell you now than sell you a kit that can't answer your question.

What Why it matters Home screen Lab E. coli Why: The standard is “0 in 100ml” North Norfolk DC and any found is treated as a “Potential danger to human health” North Norfolk DC. Home screen: Yes · E. coli Test Lab: To confirm a positive Coliforms and enterococci Why: “Coliform bacteria are found widely in the environment” North Norfolk DC. Enterococci are on the council's minimum test list below. Home screen: Not available Lab: Yes Nitrate Why: “UKHSA and Public Health Wales do not recommend anyone should regularly consume water above 50 mg/L.” DWI Home screen: Not available Lab: Yes Lead Why: Private supplies don't get the phosphate dosing mains water does, so pipes and fittings matter more (see chapter 02, point 4). Home screen: Yes · Lead Test Lab: To confirm a high result Arsenic Why: “Arsenic is primarily a risk where it is naturally occurring in local mineral deposits.” DWQR Home screen: Yes · Arsenic Test Lab: To confirm a high result pH (acidity) Why: Treatment works adjust pH partly “to reduce plumbosolvency” DWI, which is water's tendency to dissolve lead. Home screen: Not available Lab: Yes Iron and manganese Why: “Groundwater, especially, can contain dissolved metals such as iron and manganese” DWI. Home screen: Not available Lab: Yes Cloudiness (turbidity) Why: “Turbidity is caused by fine particulate matter, which can shield micro-organisms from the chemical disinfectant.” DWI Home screen: Not available Lab: Yes

If you ask the council to test a single home in England or Wales, the DWI says “the following parameters are normally tested as a minimum” DWI: conductivity, enterococci, E. coli, pH and turbidity. Councils charge for this, and set their own rates.

Screen the three big ones at home. E. coli, lead and arsenic in one kit. 3x Safety Kit · £35
04

How often to test

One clean result is a snapshot, not a guarantee. The DWI says “a test result at any given time is not necessarily representative of the water quality at all other times.” DWI

Our suggestion

Pick a month and screen in it every year, so each result compares like with like. Then add a quick E. coli check whenever one of these happens:

Rain matters most for bacteria. Food Standards Scotland notes that “heavy rainfall can significantly deteriorate the microbiological quality of various water sources” FSS.

After heavy rain? A single E. coli test is the quick retest. E. coli Test · £15.95
05

The rules where you live

Each nation has its own regulations. The big difference is between a supply that serves just your home and one that is shared, let or used by a business.

England

The law
“The Private Water Supplies Regulations 2016 and The Private Water Supplies (England) (Amendment) Regulations 2018” DWI
Just your home
“In England, a supply to a private single dwelling, where there is no commercial or public activity, is excluded from monitoring unless requested by the supply owner.” DWI
Shared supplies
“Any private water supply used for domestic purposes that supplies two or more dwellings and/or other properties must be risk assessed every 5 years, and regularly tested in accordance with the regulatory requirements by the local authority.” DWI
Lets and businesses
Where the water is used for a commercial or public activity, including in some cases a rented home or holiday let, “monitoring and risk assessment by the local authority is required.” DWI
Fees
“both the testing and risk assessment of supplies are chargeable/cost recoverable by the local authority.” DWI Each council publishes its own rates.
Who to ask
Your council's environmental health team.

Wales

The law
“The Private Water Supplies (Wales) Regulations 2017” DWI
Just your home
Not monitored unless you ask, but in Wales that exclusion applies “except where the dwelling is part of a domestic tenancy.” DWI
Shared supplies
“Any private water supply used for domestic purposes that supplies two or more dwellings and/or other properties must be risk assessed every 5 years, and regularly tested in accordance with the regulatory requirements by the local authority.” DWI
Lets and businesses
For rented homes, including short-term lets, and commercial or public use, “monitoring and risk assessment must be carried out by the local authority” DWI.
Fees
“In Wales these fees cannot exceed the maximum specified in the regulations.” DWI
Who to ask
Your council's environmental health team.

Scotland

The law
The Water Intended for Human Consumption (Private Supplies) (Scotland) Regulations 2017, which “are regulated and enforced by the Local Authorities.” DWQR
Two types of supply
“Larger PWS or those with a commercial activity are defined as Regulated supplies. Smaller PWS that only serve domestic properties are classified as Exempt supplies.” DWQR
Who to ask
“If you have a query or would like some advice about how to manage your supply, you should talk to your local authority.” DWQR
Grant
“You may be able to get a grant of up to £800 to help with the costs of improving a private supply.” mygov.scot (page last updated 2 May 2025)

Northern Ireland

The law
“The Private Water Supplies Regulations (Northern Ireland) 2017” DAERA
Who regulates
Northern Ireland's Drinking Water Inspectorate, part of DAERA: “The DWI monitors private water supplies to ensure they meet standards set within the regulations.” DAERA
Which supplies
“The regulations apply to private supplies that serve more than one household for purely domestic purposes, or are used in commercial food and drink production.” DAERA
Just your home
“If your private water supply is to a single private dwelling it is not required to be monitored by the Drinking Water Inspectorate. You can contact the environmental health department of your local council if you wish to have your supply tested.” DAERA
Owners
“Owners/users of private water supplies have responsibility under the private water supplies regulations to supply water that is wholesome and safe to drink.” DAERA

This is a summary to help you find the right rules, not legal advice. Your council has the final word on your supply.

06

If a test is positive

If E. coli is found The next 24 hours
  1. 1. Stop drinking it untreated. Under a boil water notice, the DWI's advice is to “boil it before you drink it, use it to brush your teeth, make ice cubes, prepare food, clean feeding equipment or give it to your pets” DWI, then let it cool. Or use bottled water.
  2. 2. Tell your council. Any E. coli is treated as a “Potential danger to human health” North Norfolk DC. The DWI says a council may look into a single home's supply as part of an investigation, “where for example an owner or occupier raises a concern” DWI. A lab test confirms the result.
  3. 3. Find the cause, then retest. Check the source, treatment and storage (chapter 02). Fix what you find, then retest for E. coli before you go back to drinking it untreated.

Boiling deals with germs: the DWI says it means “any bacteria or viruses that were in your water are killed or deactivated” DWI. For washing, “The water is still safe to shower and bathe in, but make sure it does not get into your mouth.” DWI

Making up baby formula? The NHS advice is to “leave the water to cool for no more than 30 minutes, so that it remains at a temperature of at least 70C” NHS.

Read my resultBacteria next steps
07 Treatment at a glance

Most private supplies need some treatment. The DWI says “In most cases some treatment will be required.” DWI We don't sell treatment systems, so this is an overview of the main types, not a recommendation.

UV disinfectionKills or inactivates germs as water passes a UV lamp. “Ensure any UV disinfection treatment is designed for drinking water.” DWIFiltrationRemoves particles, and helps disinfection work: “Ensure that water is subjected to sufficient preliminary treatment to achieve turbidity readings of <1 NTU before disinfection.” DWIChlorinationDosing a disinfectant. It has limits: “Chlorine is not recommended for disinfection of Giardia (a type of parasite) and is ineffective for Cryptosporidium (another type of parasite).” DWIpH correctionRaises the pH of acidic water, partly “to reduce plumbosolvency” DWI. Reverse osmosis at the tapUsed for chemicals such as arsenic. “RO membranes are well established as point of use treatment on private water supplies.” DWQRWater softenersKeep one tap unsoftened: “Where water is softened in this way by base exchange softening it is important to provide an unsoftened outlet for drinking purposes.” DWI

Whatever you fit, “Maintenance should always be performed by those deemed competent (trained and/or experienced and familiar with the equipment), ideally by the supplier’s servicing contractors.” DWI Then retest for E. coli.

08 Protecting your source

Stopping contamination at the source is cheaper than treating it later. These are some of the measures on the DWI's list DWI:

  • “Employ regular inspection and maintenance of septic tanks, at a frequency that is in accordance with the manufacturer’s instructions.”
  • “Installation of stock proof fencing to protect the water source from grazing animals, including rabbits and deer as well as domestic livestock.”
  • “Prevent storage and/or the spreading of manure within 50 metres of the water source.”
  • “Raise the well head or borehole head-works to at least 0.5 metres above ground level to prevent surface water or spillages of contaminated material entering into the water source.”
  • “Cover and backfill or seal any abandoned boreholes or wells to prevent surface water contamination of the aquifer.”

Keep a simple log of tests, repairs and lamp or filter changes. The DWI notes that “Accurate and detailed records, maintenances diaries, schematics and plans of a private supply is important information for the risk assessment process.” DWI

09 Buying a home with a private supply

If the home you're buying has a private supply, you become responsible for it. The DWI's advice: “Prospective buyers are recommended to request a risk assessment and testing by the local authority.” DWI Note that “there is a fee for any risk assessment or sampling carried out on request.” DWI

Questions from the DWI's list to put to the seller DWI:

  • “Has a risk assessment already been carried out by the local authority, and if so when, and what was the outcome?”
  • “What were the results of any previous sampling by the local authority?”
  • “Is there any water treatment within the property such as filters or UV disinfection units?”
  • “Has the current owner any maintenance logs or records for the supply?”
  • “Are there any deeds or agreements (legally binding or informal/customary) in place detailing who has responsibility for maintaining and operating the whole supply, or parts of it?”
Want a first look before the council visit? A home screen for E. coli, lead and arsenic. It is not a lab result. Complete Kit · £45

Near you

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Questions people ask

Private water supply questions

Short answers, with the regulator's own words where it matters.

Do I need to test my private water supply?

If it serves only your home, nobody will test it unless you ask. The DWI says “The regulations in England and Wales do not require mandatory monitoring to be undertaken at these supplies unless the local authority is requested to do so by the owner or occupier of the dwelling.” DWI Because you are responsible for it, we suggest screening at least once a year.

Who is responsible for a private water supply?

The owner or user. In Northern Ireland, for example, “Owners/users of private water supplies have responsibility under the private water supplies regulations to supply water that is wholesome and safe to drink.” DAERA Deeds can split responsibility between neighbours on a shared supply, so check them.

How often should I test a private water supply?

We suggest at least once a year, in the same month, plus an E. coli check after heavy rain, flooding or work on the supply. Quality changes through the year: the DWI says “the quality of a supply may vary with seasonal changes to the source water” DWI.

How much does council testing cost?

Each council sets its own charges. The DWI says charging rates “should be available on their respective websites and can usually be found by searching for “private water supplies” on their website.” DWI In Wales, fees have a legal maximum.

Can I use a home test kit for borehole water?

Yes, as a first screen for E. coli, lead and arsenic. A home screen is not a lab result: nitrate, pH, iron, manganese and enterococci need a lab, and a positive result should be confirmed by your council or an accredited lab.

What should I test well water for?

Start with bacteria (E. coli), then lead and arsenic. When councils test a single home on request, “the following parameters are normally tested as a minimum” DWI: conductivity, enterococci, E. coli, pH and turbidity. Add nitrate if there is farmland or a septic tank nearby.

Does the council test private water supplies?

Shared, let and business supplies, yes. In England and Wales a supply to two or more homes “must be risk assessed every 5 years” DWI. For a single home, the council tests if you ask, and charges for it. Scotland and Northern Ireland have their own rules: see chapter 05.

Is spring water safe to drink?

It can be, but don't assume it. The DWI says wells and springs “are considered surface water for the purposes of water quality risks” DWI, which means a higher risk of bacteria. Test it, and treat it if needed.

Keep reading

Is borehole, well or spring water safe to drink? Can I drill a borehole in my garden? Rules, costs and tests Borehole water treatment and private supply maintenance Can you drink rainwater? What UK households should know
Sources and how we write these pages · 19 sources · last checked 28 Sep 2026

How we write these pages. Health and safety lines are quoted word for word from the source and linked, with the date we last checked them. Home screening is a first check, not lab certification. Last reviewed 28 Sep 2026.

Where to next?

Your next step, whatever brought you here

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  • ✓ Quotes from UK regulators, linked and dated
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