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Perc Test
Find out whether your land can support a drainage field — quickly, accurately, and in full compliance with Environment Agency guidance.
If you're planning to install or replace a septic tank or small sewage treatment plant at a rural or off-mains property in Lancashire, a percolation test isn't optional — it's the essential first step. The test tells you how quickly water drains through your soil, and that result directly determines whether a drainage field (also called a soakaway) is feasible on your land, and if so, how large it needs to be. Without a valid perc test, neither your installer nor your local authority can size the drainage field correctly, and any subsequent installation could fall foul of the Environment Agency's General Binding Rules for domestic sewage discharge.
The General Binding Rules set out the legal framework for how treated effluent from septic tanks and sewage treatment plants can be discharged to the ground in England. Among other things, they require that drainage fields are designed and sized in accordance with the methods described in BS 6297:2007, the British Standard that governs the design of drainage systems for small domestic and commercial sites. A properly conducted percolation test is central to that standard — there's no shortcut, and a guess will almost certainly cause problems down the line.
So how does the test actually work? Our team visits your site, digs trial pits to a specified depth in the area where the drainage field is proposed, and carries out a series of timed water-infiltration tests. We repeat the test at multiple locations across the proposed drainage area, because soil can vary significantly even within a small plot. The results give us a percolation value (Vp), which is then used to calculate the minimum surface area your drainage field must cover. We record everything clearly so you — and your installer or planning officer — have a fully documented result to work from.
Lancashire's landscape is wonderfully varied, and that variation matters enormously when it comes to perc testing. Heavy clay soils are common across parts of the Fylde Coast and the lower Ribble Valley, and they can drain so slowly that a conventional drainage field simply won't work — meaning an alternative discharge route may need to be explored. Conversely, the sandier soils found in areas like the West Lancashire plain can drain too freely, which presents a different set of challenges for correct sizing. Our local experience across postcodes from PR1 to PR8 and beyond means we understand what to expect and can advise you honestly on the ground conditions before any groundwork is committed to.
Once the test is complete, we provide you with a clear written report summarising the method used, the results at each test location, and the calculated Vp value. If the results indicate that a drainage field is viable, we can also discuss next steps — including connecting you with drainage design and installation support. If the ground conditions aren't suitable, we'll explain what your realistic options are so you can plan accordingly. Our goal is to give you an accurate picture you can act on, not just a piece of paper.
Why choose Lancashire Septics Ltd
- BS 6297:2007-compliant percolation testing carried out by experienced drainage specialists
- Full written report with Vp values and drainage field sizing guidance included
- Local knowledge of Lancashire soil types across rural and semi-rural postcodes
- Tests conducted at multiple locations on site for reliable, representative results
- Supports compliance with the Environment Agency's General Binding Rules for sewage discharge
Pricing
Every job is different. Tell us about your property and we'll send a tailored quote — usually the same working day.
Request a free quoteWhat's included
Residential Perc Testing
Percolation testing for homeowners installing or upgrading a septic tank or treatment plant at a domestic property. Covers all required trial pits, timed infiltration tests, and a written results report.
New-Build & Planning Support
Perc testing carried out ahead of planning applications or building regulation submissions, providing the drainage field viability evidence your architect or surveyor needs.
Replacement System Assessment
If an existing soakaway or drainage field has failed, we test the surrounding ground to determine whether a replacement drainage field is viable in an alternative location on your land.
Frequently asked questions
- Do I actually need a percolation test, or can my installer just estimate?
- Estimating isn't acceptable under BS 6297:2007, which is the British Standard referenced by the Environment Agency's General Binding Rules. Without a properly conducted perc test, your drainage field cannot be correctly sized, which means it could fail prematurely or put you in breach of the rules for discharging sewage effluent to the ground. A valid test result protects both your installation and your legal compliance.
- How long does a percolation test take?
- On most residential plots, the on-site work takes between two and four hours, depending on the number of test locations required and how the soil behaves during the infiltration stages. We'll let you know roughly what to expect when we confirm your booking. The written report is typically turned around shortly after the site visit.
- What happens if my soil fails the perc test?
- If your soil drains too slowly — or in some cases too quickly — to support a conventional drainage field, that doesn't necessarily mean you're out of options. We'll explain what the results mean in plain terms and discuss possible alternatives, which might include a different discharge route or a different type of system suited to your ground conditions. We'd rather give you an honest answer early than let you invest in something that won't work.
- How does pricing work for a percolation test?
- Every site is a little different — plot size, access, the number of trial pits needed, and location all play a part in determining the cost. Rather than publishing a one-size-fits-all figure that may not reflect your situation, we prefer to give you a proper quote based on the details of your specific site. You can request a quote by emailing support@lancashireseptics.co.uk or by calling +441616947241 — we'll come back to you promptly.
- Do I need to do anything to prepare the site before your team arrives?
- It helps if the area where the drainage field is planned is reasonably accessible — ideally with no parked vehicles or stored materials directly over the proposed test locations. If you're unsure which part of your garden or land is being considered, your installer or architect should be able to mark it out in advance. Our team will talk you through any specific preparation when we book the visit.
- Can the report be used for a planning application?
- Yes — our written report documents the test methodology, individual location results, and the calculated percolation value in a format that planning officers and building control surveyors typically require. If your architect or planning consultant has specific formatting requirements, let us know when you book and we'll do our best to accommodate them.
Get in touch
Tell us what you need
Fill in the form and we'll be in touch within one working day with a quote or booking slot. For emergencies please call us - it's the fastest way to get a truck on site.
Phone: 0161 694 7241