Private Water Supply Regulations in the UK: Testing Requirements and Compliance Obligations

Approximately 1-3% of UK residents depend on private water supplies rather than mains connections, with these supplies predominantly serving rural properties across England, Wales, Scotland, and Northern Ireland. Each nation operates distinct regulatory frameworks, though all derive from EU Drinking Water Directive requirements implemented through national legislation between 2016 and 2018. The Drinking Water Inspectorate oversees England and Wales, while Scotland has its own regulator and Northern Ireland places responsibility directly with DAERA.

The regulatory burden varies dramatically depending on supply classification. Commercial uses trigger comprehensive monitoring requirements regardless of volume, while single owner-occupied dwellings face minimal mandatory intervention. Failure rates for bacterial contamination run substantially higher than public supplies—E. coli detection occurs in 4-18% of samples depending on supply type and nation, compared to near-zero rates in mains water. Property owners facing compliance issues may spend £2,000-£8,000 on treatment systems, with ongoing maintenance adding £300-£600 annually.

Regulatory frameworks diverge significantly across the four UK nations

England operates under the Private Water Supplies (England) Regulations 2016, as amended in 2018, with enforcement delegated to 207 local authority environmental health departments. Supplies are classified according to which regulation applies. Regulation 8 covers private distribution systems where mains water is redistributed through private infrastructure. Regulation 9 applies to any supply serving 10m³ daily or more, 50+ persons, or any commercial or public activity—this includes hotels, B&Bs, campsites, food premises, and holiday lets. Regulation 10 covers smaller domestic supplies. Single owner-occupied dwellings are exempt from mandatory monitoring unless specifically requested or the property is rented.

Scotland maintains a dual system through two separate statutory instruments. The Private Water Supplies (Scotland) Regulations 2006 govern smaller supplies, while the Water Intended for Human Consumption (Private Supplies)(Scotland) Regulations 2017 cover larger ones. The distinctive Type A/Type B classification separates regulated commercial supplies from smaller domestic ones. Scotland has 22,459 registered private supplies serving approximately 185,850 people, making it the UK nation with the highest proportion of private supply users. The Drinking Water Quality Regulator for Scotland provides independent oversight separate from local authority enforcement.

Wales follows England’s approach closely through the Private Water Supplies (Wales) Regulations 2017, using a four-category system under DWI oversight on behalf of Welsh Ministers. However, the registration gap presents challenges—while 14,904 supplies are registered, Welsh Government estimates an additional 41,764 unregistered supplies exist. Natural Resources Wales provides catchment information for risk assessments but holds no direct regulatory authority.

Northern Ireland differs most substantially from the other nations. The Private Water Supplies Regulations (Northern Ireland) 2017 place regulatory responsibility directly with DAERA rather than district councils, with DWI operating within NIEA. Critically, only supplies serving multiple households or used for commercial food and drink production fall under monitoring requirements—single private wells serving one dwelling are explicitly exempt from regulation. This reflects Northern Ireland’s infrastructure context, where less than 1% of water comes from private supplies compared to higher proportions elsewhere.

Risk assessments must be conducted every five years for all regulated supplies across the UK. These assessments identify hazards in the catchment, evaluate supply adequacy, and determine appropriate monitoring frequency. The practical reality shows significant compliance gaps—only 39.3% of English supplies requiring assessment had current ones in 2024 data, while Wales achieved 45.1% coverage. Scotland’s data shows better performance for larger Type A supplies but substantial gaps remain for smaller Type B installations.

Water quality standards establish strict limits for microbiological and chemical parameters

The parametric values set in Schedule 1 of each nation’s regulations define what constitutes safe drinking water, with microbiological standards being the most critical for private supplies given elevated contamination risks.

E. coli must show zero detection per 100ml—any presence constitutes a failure requiring investigation and remedial action. The same zero-tolerance standard applies to enterococci and, where relevant, Clostridium perfringens. These indicator organisms signal faecal contamination and potential presence of pathogens. Coliform bacteria also have a zero parametric value, though they serve primarily as process indicators for treatment effectiveness rather than direct health markers. The distinction matters because coliforms may survive longer in distribution systems than E. coli, providing early warning of contamination or treatment failure.

Chemical parameters vary by health significance and typical occurrence in private supplies. Nitrate must not exceed 50 mg/l, with nitrite limited to 0.50 mg/l at the consumer’s tap or 0.10 mg/l leaving treatment works. This presents particular concern in agricultural areas where 2024 English data showed an increased failure rate of 8.42%, up from 6.54% the previous year. Nitrate contamination typically originates from fertiliser application and cannot be removed by boiling or standard filtration, requiring ion exchange or reverse osmosis treatment.

Lead is limited to 10 µg/l under current standards, though no safe level exists for this neurotoxin. The standard reflects achievable limits rather than health-based thresholds. Properties with lead pipes or lead-containing solder in older plumbing systems often struggle to meet this limit, with pipe replacement representing the only robust long-term solution. Temporary measures like flushing before use or phosphate dosing provide partial mitigation but don’t eliminate exposure.

Arsenic has the same 10 µg/l limit, significant in areas with certain geological formations including parts of Cornwall, Devon, and Scotland. Copper is permitted up to 2.0 mg/l, fluoride to 1.5 mg/l, and manganese to 50 µg/l. Iron, while not directly harmful, has a 200 µg/l limit due to aesthetic impacts including staining and metallic taste.

Physical parameters establish bounds for both aesthetic acceptability and treatment effectiveness. pH must fall between 6.5 and 9.5—values below this range cause copper pipe corrosion and lead dissolution, while high pH can indicate contamination from construction materials or inadequate treatment. Turbidity should not exceed 4 NTU, which matters critically because suspended particles can shield pathogens from UV disinfection and interfere with chlorination. Colour is limited to 20 mg/l Pt/Co, conductivity to 2,500 µS/cm, with taste and odour required to be acceptable with no abnormal change.

Monitoring requirements scale with supply classification and volume

Sampling divides into Group A (check monitoring) covering basic microbiological and operational parameters, and Group B (audit monitoring) testing the full parameter suite including metals, pesticides, and other compounds. For Regulation 9 supplies, Group A sampling occurs at minimum annually, with frequency scaling by volume. A supply of 10m³/day or less requires two Group A and one Group B sample annually. Larger supplies need proportionally more frequent testing according to tables in the regulations.

Regulation 10 supplies serving purely domestic purposes require testing at least every five years with basic parameters: conductivity, enterococci, E. coli, pH, and turbidity. This reduced frequency reflects lower risk to public health when contamination would affect only the property owner and their household. However, owners should consider more frequent voluntary testing given the substantial failure rates observed in regulatory sampling—waiting five years between tests means extended exposure if problems develop.

The 2018 amendments to the English regulations introduced reduced monitoring provisions intended to focus resources on problem supplies. Where results remain below 60% of parametric values for three or more years with supportive risk assessment, frequency may be reduced. Results below 30% may permit ceasing monitoring for that parameter entirely. These provisions aim to reduce regulatory burden for consistently compliant supplies, though E. coli must always be monitored regardless of historical performance—no reduction or cessation is permitted for this critical indicator.

All sampling and analysis for regulatory compliance must use UKAS-accredited laboratories holding ISO/IEC 17025 accreditation under the Drinking Water Testing Specification. This requirement ensures proper chain of custody, sample handling according to EN ISO 19458, and analytically defensible results that can support enforcement action if necessary. The DWI maintains a list of approved analytical services, and UKAS provides a searchable directory of accredited organisations.

Sample timing significantly affects interpretation of results. Surface-water-influenced supplies show elevated contamination risk after heavy rainfall when runoff carries livestock faeces and other pollutants into source waters. Agricultural areas see nitrate peaks following fertiliser application, typically in spring and again after autumn applications. Lead samples require random daytime sampling without flushing to capture actual consumer exposure rather than best-case flushed results that would underestimate typical intake.

Testing costs range from basic packages to comprehensive analytical suites

Local authority charges for statutory activities are capped by regulation to prevent excessive cost recovery. Risk assessments can cost up to £500 per supply, with actual charges typically ranging £200-£450. Shropshire Council charges £429, reduced to £390 if owners complete a pre-questionnaire, while East Devon charges £300 including sample collection. Sampling visits are capped at £100, typically charged at £67-£100. Investigation work following failures is limited to £100 per hour. Analysis costs up to £25 for check monitoring per sample or £500 for audit monitoring.

Private laboratory testing offers alternatives for voluntary testing or where owners wish to supplement regulatory sampling. Basic microbiological packages covering E. coli, coliforms, and colony counts run £45-£70 from commercial laboratories. A 12-parameter test costs £95-£150, while comprehensive 27+ parameter suites range £150-£200. Full audit monitoring covering 30+ parameters with metals, pesticides, and radioactivity costs £275-£500. Individual parameters like lead typically cost £25-£40 when tested separately.

Major UKAS-accredited laboratories operating across the UK include Eurofins Environmental Services, ALS Environmental, Scottish Water Scientific Services, and Feedwater Ltd. Regional laboratories often provide faster turnaround and local knowledge of typical contamination issues. Some local authorities maintain their own accredited laboratories and will analyse samples from neighbouring authority areas, sometimes at lower cost than commercial providers.

Sample collection requires attention to detail to ensure representative results. Taps should be thoroughly cleaned with sterile wipes before sampling, with exterior surfaces wiped down to prevent contamination during bottle filling. For microbiological sampling, the tap should run for 30-60 seconds to clear the immediate fixture, then samples collected without flushing the entire system. Chemical sampling may require longer flushing depending on the parameter—lead testing specifically requires no flushing to capture worst-case exposure. Bottles must be filled according to laboratory instructions, typically to a marked line and without overfilling, then chilled and delivered to the laboratory within specified timeframes, usually 24-48 hours.

Enforcement mechanisms progress from improvement requirements to use prohibition

When sampling reveals failures, local authorities must investigate under Regulation 16 to determine the cause and whether the supply poses a health risk. The response pathway depends on severity and affected parameters.

Contamination presenting potential danger to human health triggers mandatory action under Regulation 18. Local authorities must serve a notice specifying the grounds for concern, restricting or prohibiting use as appropriate, and requiring remedial steps within specified deadlines. These notices remain in force during any appeal to protect consumers from continued exposure. Appeals to Magistrates’ Court must be lodged within 28 days of service. Courts may cancel, confirm, or modify notices based on evidence presented but cannot suspend them pending appeal without specific order—this differs from planning enforcement where appeals typically suspend notices.

Supplies deemed unwholesome but not immediately dangerous allow a more measured approach. The local authority may grant 28 days for voluntary remediation before serving a Section 80 notice under the Water Industry Act 1991. Recipients have at least 28 days for written representations before the notice takes effect. Objections go to the Secretary of State via the DWI Chief Inspector for determination, potentially including a local inquiry where disputes involve substantial technical or factual questions.

Authorisations under Regulation 17(2) permit temporary non-compliance for up to three years where a supply fails non-health-based parameters like aesthetic standards, remediation plans are in place and being implemented, and no health risk exists. This provides breathing room for complex improvement projects requiring staged implementation or where connection to public supply is being arranged but takes time to complete. Authorisations are not available for E. coli or other direct health indicators.

Treatment system costs depend on the specific problems identified. UV disinfection systems for bacterial contamination run £300-£1,500 for domestic units treating typical household flows. These require £120-£200 annual maintenance for lamp replacement and quartz sleeve cleaning. However, UV only works effectively on water with turbidity below 1 NTU, so sediment filtration as UV pre-treatment costs an additional £200-£400 plus £50-£100 annual cartridge replacement.

Iron and manganese removal systems requiring backwashing media filters cost £1,200-£3,000 installed, varying with flow rate requirements and whether both contaminants need addressing. These systems need backwashing every few days, using 50-100 litres per cycle, which can strain limited sources. pH correction for acidic water runs £500-£1,500 depending on whether simple neutralising filters suffice or calcium/magnesium injection is required. Comprehensive multi-stage systems addressing bacterial contamination plus multiple chemical parameters cost £3,000-£8,000 installed, with annual maintenance of £300-£600 depending on complexity.

Criminal penalties apply for non-compliance with statutory notices. Summary conviction in Magistrates’ Court permits fines up to the statutory maximum, while conviction on indictment in Crown Court allows unlimited fines. Local authorities can also execute works in default where recipients fail to comply with improvement notices, recovering costs plus administrative charges from the responsible person. This power sees limited use in practice due to cost recovery difficulties, but provides ultimate enforcement backstop.

Property transactions require comprehensive disclosure and face financing challenges

Sellers must disclose private water supply status on the TA6 Property Information Form, with failure to reveal known problems potentially actionable as misrepresentation for up to six years post-sale under Consumer Protection from Unfair Trading Regulations 2008. This liability extends beyond simple non-disclosure to misleading statements about water quality or supply adequacy.

Standard conveyancing searches identify whether property connects to public or private supply but provide limited detail on condition or compliance status. The CON29DW water and drainage search confirms the supply type and whether public connection is available, but rarely includes historical test results or enforcement action details. Environmental searches may flag private water supply issues if contamination incidents have been reported to environmental regulators. Local authority searches can reveal outstanding enforcement notices but may not capture historic issues that were resolved.

Buyers should request specific information beyond standard searches. Source type and location matters for assessing sustainability and contamination risk—a shallow well in a valley bottom faces different challenges than a deep borehole on elevated ground. Where shared supply arrangements exist, written agreements should define maintenance responsibilities, cost sharing, access rights, and dispute resolution. Recent water test results from UKAS-accredited laboratories provide evidence of current quality, though a single test represents only that moment—seasonal variation may affect results. Local authority risk assessment outcomes identify vulnerabilities even if current tests show compliance. Treatment systems installed should come with commissioning records, maintenance logs, and remaining warranty information. History of failures or quality issues helps assess likelihood of recurrence. Seasonal variations in quality or sufficiency affect property usability—supplies adequate in winter may fail during summer droughts. Outstanding improvement notices or authorisations for temporary non-compliance directly affect property value and usability.

Mortgage lenders increasingly require water quality evidence before approving finance on private water supply properties. Many demand recent testing results demonstrating safe drinking water standards, and some impose ongoing testing as a mortgage condition with results provided annually. The available lender pool is smaller for private supply properties, with many mainstream providers declining applications entirely or referring to specialist underwriters for case-by-case assessment. Retentions may apply until compliance is confirmed through independent testing. Properties with outstanding enforcement notices face particular difficulty securing finance—most lenders refuse until issues are resolved.

Insurance for private water supply properties typically covers underground pipework and escape of water claims under standard policies, but owners should declare private supply status to insurers during application. Treatment equipment may need specific inclusion as it’s not automatically covered. Water quality issues causing damage might be excluded, and gradual deterioration from wear and tear is typically excluded regardless of cause. Shared supply arrangements only cover the owner’s portion of infrastructure—damage to shared sections may require complex claims involving multiple parties.

Property valuations can be adversely affected by private water supply issues, particularly outstanding enforcement notices, required treatment system costs, or documented quality problems. Well-maintained, compliant supplies with comprehensive documentation and recent satisfactory test results may have minimal value impact compared to mains-connected properties in similar areas. Problem supplies requiring substantial remediation investment can significantly reduce marketability, potentially requiring price reductions of 10-20% or more depending on remediation costs relative to property value.

Scotland provides substantial grant support unavailable in other UK nations

The financial assistance landscape varies dramatically across the four nations, with Scotland standing alone in providing systematic support for private water supply improvements.

The Private Water Supplies (Grants)(Scotland) Regulations 2006 provide non-means-tested grants of up to £800 per property for improvement works addressing quality failures or inadequate supplies. Applications must be made before starting work, and the grant covers treatment equipment installation, source improvements, and storage tank replacement, but excludes ongoing maintenance or connection to mains supply. For essential works exceeding £1,200, an additional 50% of costs beyond the initial £800 may be funded. Households receiving specified benefits may receive 100% funding regardless of cost. Local authorities administer these grants on behalf of Scottish Ministers, with processing times typically 6-8 weeks.

The £800 figure has remained unchanged since 2006 introduction, meaning significant erosion by inflation—the equivalent figure in 2024 terms would be approximately £1,300, though no uplift has occurred despite repeated requests from rural communities and local authorities. Even at reduced real-terms value, this support significantly helps Scottish householders compared to those elsewhere in the UK facing identical challenges without any equivalent assistance.

Scotland’s Private Water Supply Connections Project separately pilots support for communities seeking public network connection rather than source improvement. This covers water impact assessments up to £25,000 and contributes toward network extensions to property boundaries, though individual property connection costs remain the owner’s responsibility. Several Highland and Argyll & Bute communities have benefited, with projects involving 10-30 properties proving most viable for shared infrastructure costs.

England has no equivalent national grant scheme for domestic private water supply improvements. The Farming Investment Fund provides Water Management Grants addressing agricultural irrigation efficiency with minimum grants of £35,000 at 40% of eligible costs, but explicitly excludes domestic drinking water supplies. The Water Restoration Fund supports farmer groups improving freshwater habitats through measures like cattle drink alternatives and riparian fencing, but has no domestic supply application. Some local authorities may offer discretionary assistance for vulnerable households under housing improvement powers, but this is inconsistent, means-tested, and typically limited to grants under £5,000.

Wales lacks specific private water supply improvement schemes despite similar rural demographics to Scotland. Welsh Water’s Community Fund provides up to £5,000 for community projects benefiting areas they serve, but prioritises education and recreation rather than water supply infrastructure. Environmental schemes offer small grants for habitat improvement, but neither specifically targets domestic private water supply upgrades for quality compliance.

Northern Ireland has no dedicated private supply improvement grant despite substantial rural populations in areas like Fermanagh and Tyrone with significant numbers of private supplies. The Water Quality Improvement Strand of the Environmental Challenge Fund offers £5,000-£30,000 for community water quality projects, but restricts eligibility to not-for-profit organisations rather than individual property owners. This means householders facing £5,000-£15,000 costs for comprehensive treatment systems receive no systematic support.

This funding disparity creates significant inequity between UK nations. Scottish householders facing enforcement action for supply failures can access £800-£5,000+ in public funding toward remediation costs, while English, Welsh, and Northern Irish householders facing identical requirements and similar costs receive nothing. Rural MPs in non-Scottish constituencies have periodically raised this inconsistency without achieving policy change.

Bacterial contamination and agricultural pressure drive most compliance failures

2024 data from English local authorities reveals persistent challenges across private supplies despite regulatory oversight. E. coli contamination occurred in 4.46% of samples—while improved from 4.93% in 2023, this still represents substantial risk compared to near-zero rates in public supplies where water company targets typically allow no more than 0.01% positive samples. Wales recorded even higher rates at 8.97% of samples containing E. coli. Scotland’s data distinguishes between supply types, with larger Type A supplies showing 4.2% failure but smaller Type B exempt supplies reaching 17.9% non-compliance.

Coliform bacteria failed in 10.31% of English samples, indicating treatment inadequacy or distribution system integrity issues even where E. coli is absent. This matters because coliforms survive longer in pipework than E. coli, providing early warning before faecal contamination reaches taps. The gap between coliform and E. coli rates suggests many supplies have intermittent problems not captured in point-in-time sampling.

Nitrate failures rose to 8.42% from 6.54%, reflecting agricultural intensification pressure on groundwater sources. This parameter cannot be removed by boiling or standard filtration, requiring ion exchange or reverse osmosis treatment costing £1,500-£4,000 installed plus £200-£400 annual membrane or resin replacement. The increase coincides with expanded fertiliser use following 2022-23 price volatility and supply concerns.

Manganese failed in 4.79% of samples, causing aesthetic issues including black staining of fixtures and laundry, metallic taste, and bacterial growth in distribution systems. Treatment requires oxidation-filtration systems typically costing £1,200-£2,500 installed with £150-£250 annual media replacement. Lead exceeded the 10 µg/l limit in 2.1% of samples, though this likely understates the problem as sampling protocols may involve partial flushing that reduces measured concentrations below actual consumer exposure.

Sources of bacterial contamination fall into several categories. Animal faeces from livestock or wildlife accessing catchments directly introduces pathogens—cattle, sheep, and deer attracted to water sources can contaminate supplies serving multiple properties downstream. Inadequate wellhead protection allows surface water ingress during heavy rainfall, with poorly sealed well caps or missing sanitary seals providing entry points. Faulty borehole casings and seals in older installations permit shallow contaminated water to bypass deeper protected zones. Poorly fitted storage tank lids attract vermin including rats and birds, with droppings falling directly into stored water. Proximity to septic tank systems creates risk, particularly where soakaways are undersized or failing, with the regulatory requirement for 50m separation often violated in existing installations.

Effective protection requires multiple barriers. Fencing to exclude livestock should extend at least 10m from sources for springs and wellheads, with larger catchment protection for surface water intakes. Surface drainage must be directed away from sources, potentially requiring French drains or berms to prevent ponding. Properly sealed and raised wellheads with lockable covers prevent both surface water and animal access. Maintained sanitary seals on all infrastructure including storage tanks, valve chambers, and pipework entry points prevent contamination during routine access. These measures collectively cost £500-£2,000 depending on site conditions but substantially reduce failure risk.

Seasonal variation affects multiple parameters. Heavy rainfall increases turbidity and bacterial contamination in surface-influenced supplies. Drought conditions concentrate contaminants while reducing dilution, particularly affecting nitrate and chloride levels. Spring snowmelt mobilises accumulated pollutants from frozen ground. Agricultural activities have distinct seasonal patterns—spreading seasons for slurry and manure, fertiliser applications in spring and autumn, and livestock movements between pastures all create elevated risk periods.

Professional assistance requires qualified specialists for different aspects

Finding competent professional help for private water supply issues requires distinguishing between different specialisms and qualifications. Water testing requires UKAS-accredited laboratories, with the UKAS directory providing searchable access. The Drinking Water Inspectorate maintains a list of approved analytical services specifically for regulatory compliance testing.

Source assessment and hydrogeological investigation needs appropriately qualified geologists or hydrogeologists. The Geological Society’s directory lists chartered geologists meeting professional competence standards. The Hydrogeological Group has over 1,000 members specialising in groundwater assessment, borehole design, and water supply sustainability. For new borehole drilling or existing well rehabilitation, the British Drilling Association and Well Drillers Association can identify qualified drilling contractors with appropriate equipment and experience.

Treatment system design and installation requires specialists in water treatment rather than general plumbers. The Chartered Institution of Water and Environmental Management (CIWEM) maintains specialist panels for water supply and quality, with members holding relevant qualifications and experience. Some local authorities maintain lists of competent contractors who regularly install compliant systems in their areas, though they cannot recommend specific companies.

When disputes arise with local authorities over risk assessments, monitoring requirements, or enforcement notices, the first step is informal discussion with the case officer and their manager. If this doesn’t resolve matters, formal complaints through the local authority’s complaints procedure establish a record. For technical disputes about water quality standards or monitoring interpretation, the DWI will consider representations from property owners or their representatives. Legal advice becomes relevant when enforcement action threatens prohibition of use or criminal prosecution, with solicitors experienced in environmental and regulatory matters offering most relevant expertise.

Record-keeping serves multiple purposes beyond regulatory compliance. All risk assessment reports should be retained for at least 30 years, as they document hazards and control measures that affect property value and liability. Sampling results and laboratory certificates establish baseline conditions and trends over time, helping distinguish new problems from chronic issues. Treatment system installation records including commissioning certificates, system schematics, and warranty documentation prove proper specification and installation. Maintenance logs demonstrate due diligence and help troubleshoot problems. Any enforcement notices or correspondence with regulatory authorities may be required during property sales or following system changes.

Digital record-keeping with cloud backup ensures information survives property transfers and equipment failures. Scanning historic paper records preserves information from fading or water damage. For shared supplies, one property should be designated as record holder with copies provided to all users, avoiding information loss when individual properties change hands.

Conclusion

Private water supply regulation in the UK reflects genuine health risks associated with unregulated sources. With E. coli failure rates of 4-18% compared to near-zero in public supplies, the regulatory framework serves protective functions despite compliance costs. The critical insight for rural property owners is that regulatory classification determines obligations—commercial uses trigger comprehensive Regulation 9 requirements regardless of scale, while purely domestic owner-occupied supplies face minimal mandatory intervention.

Scotland’s grant scheme providing up to £800-£5,000+ for improvements stands in stark contrast to England, Wales, and Northern Ireland where no equivalent systematic support exists. This disparity means Scottish householders face substantially lower net costs for identical remediation work, creating significant inequity between nations ostensibly sharing harmonised water quality standards.

Proactive engagement typically proves more cost-effective than reactive compliance following enforcement action. Risk assessments costing £200-£500 identify vulnerabilities before they cause failures requiring £2,000-£8,000 remediation systems. Treatment systems sized and specified correctly during installation avoid costly modifications. Documentation maintained throughout ownership facilitates property transactions and demonstrates due diligence reducing liability exposure.

For those purchasing rural property with private supplies, key due diligence steps include obtaining recent UKAS-accredited test results, reviewing local authority risk assessment outcomes, inspecting treatment systems and maintenance records, understanding any shared supply arrangements with written agreements, and confirming mortgage lender requirements before proceeding. These measures prevent costly surprises and ensure informed decisions about a fundamental aspect of rural property ownership. The lower property values sometimes associated with private supplies may be offset by absence of water rates, but only where supplies are well-maintained and compliant—problem supplies simply represent liabilities rather than savings.