Planning a borehole: from first enquiry to a working supply

Start with the job the borehole must do, rather than a target drilling depth. A useful project brief sets out demand, site constraints, permissions, testing and the equipment needed to turn a hole in the ground into a working installation.

This guide concentrates on water-supply boreholes for homes, farms and businesses. It also explains where heating and ground-investigation projects need a different brief. It is a planning checklist, not a design for an individual site.

1. Define the purpose and demand

Write down who will use the water, what they will use it for and what happens if the supply stops. Drinking water for a household, livestock water, irrigation and a food-production process have different requirements. A holiday let or business use also needs to be identified when discussing private-water-supply responsibilities.

For a water supply, ask the designer to distinguish:

• Daily demand: the total volume needed over a day, including busy or dry periods.
• Peak demand: the flow needed when several outlets or processes operate together.
• Delivery pressure: the pressure required at the point of use, allowing for the layout of the installation.
• Resilience: whether storage, an alternative supply, alarms or backup power are needed.
• Future use: additional buildings, livestock, irrigation or commercial activity that could change the design.

Storage can help balance intermittent demand, but it does not create additional groundwater. For example, a large short-duration demand and a modest continuous demand may have the same daily total but need different pumps, controls and storage arrangements. Ask for the design assumptions in writing.

2. Establish what is known about the ground

A desktop assessment can help identify likely formations, nearby borehole records, groundwater conditions and possible contamination or mining constraints. Commission advice appropriate to the scale and risk of the project. A hydrogeologist can help assess whether further investigation is justified and what the investigation should establish.

Treat a neighbouring borehole as evidence to discuss, rather than a promise of the same depth, yield or water quality. Ask which information applies to your exact site, which information is inferred and what remains uncertain until drilling and testing.

Useful questions for an initial assessment include:

• What is the likely target formation, and why?
• What depth range is being considered, and what would change that assessment?
• What nearby supplies, watercourses or sensitive features need consideration?
• Are there signs of contamination, made ground, old workings or other constraints?
• What are the reasons to proceed, investigate further or stop before drilling?

An assessment is most useful when it sets out uncertainty and a decision process. Avoid treating an indicative depth on an early quotation as an engineered final design.

3. Check permissions before booking the rig

There is no single permission covering every UK borehole project. Establish separately the position on land access, planning, drilling and investigation, water abstraction, test-water discharge and drinking-water use. Ask who will make each enquiry, prepare an application and hold the resulting approval.

England: the Environment Agency's abstraction guidance says taking more than 20 cubic metres a day is likely to require a licence. Its exemption for 20 cubic metres or less has conditions, including aggregation across abstraction points forming the operation. One cubic metre is 1,000 litres. Separately, its groundwater investigation guidance uses “20 cubic metres or more” for investigation consent. If your proposal is at the boundary, obtain advice from the Agency rather than assuming the two tests are identical.

Wales: consult Natural Resources Wales about groundwater investigation consent and subsequent abstraction requirements. Permission for an investigation does not guarantee permission to operate the supply.

Scotland: use SEPA's current activity-specific authorisation guidance. Its small-borehole construction category has limits and conditions covering the construction and intended use. Do not apply England's threshold to a Scottish project.

Northern Ireland: check the DAERA/NIEA abstraction application guidance. Its authorisation system has its own thresholds and conditions; confirm both the proposed operation and any testing arrangements.

Ask the local planning authority about your proposal, including associated structures and plant. A small abstraction exemption does not establish that planning, pollution prevention or other requirements are satisfied. Recheck the linked guidance when commissioning work, because rules and application processes can change.

4. Agree a practical and protective location

The most convenient corner of a site may not be the right position. Discuss protection from potential pollution, flooding and surface runoff, the route to the buildings supplied, and access for future maintenance. The British Geological Survey's construction guidance identifies potential pollution sources such as septic systems, fuel storage and agricultural activities, and explains the importance of appropriate casing and sealing.

Give the contractor a site plan showing buildings, boundaries, drains, tanks, overhead lines, known underground services and existing water supplies. Make clear which details are confirmed and which are approximate. The contractor needs a safe system for locating and avoiding services: HSE guidance describes planning, service plans, locating equipment and safe working practices. A sketch supplied by an owner does not replace those checks.

Confirm rig and vehicle access, turning space, height restrictions, ground-bearing conditions, working space, noise arrangements and where equipment can remain. Include access for later pump removal or repairs. Agree protection for drives and landscaping, and the standard of reinstatement included in the price.

5. Budget for a complete supply

Separate the investigation cost from the cost of a working installation. Ask for allowances covering drilling and borehole completion, pump testing, laboratory analysis, the permanent pump, power, controls, treatment where required, storage, pipework, commissioning and reinstatement. Include professional advice and application costs where relevant.

Ask what is payable if drilling stops without a usable supply. Agree a maximum authorised depth or expenditure, decision points and a written process for approving extra work. An honest budget includes uncertainty; it should not make every unexpected condition an open-ended instruction to spend more.

For the ongoing budget, ask about electricity use, inspection, sampling, treatment consumables, servicing, replacement equipment and any applicable abstraction charges. Compare these costs with the alternatives available to your property. Avoid a savings forecast that assumes a successful supply, zero maintenance or an unchanging water demand.

6. Set the test and acceptance plan

Finding water during drilling is a milestone, not the complete acceptance test. Ask what pumping test is proposed, what measurements and report you will receive, and who will interpret whether the results meet the agreed demand. Discuss how the assessment addresses seasonal uncertainty and the effect on nearby water features where relevant.

In that discussion, yield means the flow the source produces under the stated conditions; drawdown is the fall in water level during pumping. Ask what the water-level recovery after pumping shows and how the recommended operating rate was chosen. A short demonstration of water coming from the hole is not equivalent to a documented assessment of supply performance.

For drinking-water use, involve the appropriate private-water-supply authority early. In England and Wales, the DWI's guidance on new supplies explains the local authority's role. In Scotland, consult your council using the private-supply guidance. In Northern Ireland, check DAERA's private-supply arrangements.

Agree who will arrange suitable sampling and analysis, interpret the results, specify any treatment and confirm commissioning checks. Clear-looking water and a pump that runs do not establish drinking-water safety. Do not bring a new drinking-water supply into use on that basis.

7. Plan the handover and ownership

Before work starts, agree the records you will receive: the final borehole location, construction details, drilling log, test results, equipment schedule, commissioning information, permissions and operating instructions. Ask who will handle applicable drilling notifications and deposit records. BGS explains its notification and records role; that role does not make it the planning or abstraction authority.

Identify who will own and maintain shared infrastructure, pay running costs and authorise repairs. Where a supply crosses land boundaries or serves more than one property, obtain appropriate advice on access and supply agreements rather than relying on an informal understanding.

For heating projects, first establish whether the design is open loop or closed loop and who is responsible for the heat demand and ground-loop design. England has separate environmental-permit guidance for closed-loop systems. A water-supply checklist alone is not sufficient for a heating installation. For ground investigation, start with the engineer's investigation scope and required samples, tests and report.

Your brief for a first enquiry

Send the contractor the site address and plan, intended use, demand information, access photographs, existing reports, known constraints and desired timescale. Ask for the next investigation step, its deliverables and its cost before committing to the entire installation.

Once you have a defined brief, use it unchanged when requesting proposals from different companies. That gives you a useful basis for comparing what each contractor is actually offering.