Percolation Tests carries out BRE365 soakaway percolation testing and foul infiltration testing in Stafford and across the surrounding villages. We are based in Wolverhampton, about twenty minutes down the M6, so Stafford is genuinely local work for us rather than a long trip — which is why we can usually get to site quickly and keep the cost sensible.
Ground conditions around Stafford
Stafford sits on the Sherwood Sandstone Group, which in principle is one of the better formations to be building a soakaway into — sandstone can take water readily. The complication is what sits on top of it. Much of the town and the land around it is blanketed by superficial deposits: glacial till and sands and gravels left behind by ice, and alluvium along the valleys of the Sow and the Penk.
Those deposits are the reason results vary so much across short distances here. A plot on clean sand over sandstone can give an excellent infiltration rate, while a site a few hundred metres away sitting on a lens of boulder clay may barely drain at all. Low-lying ground near the Sow can also sit close to the water table, and BRE365 requires the base of a soakaway to stay clear of groundwater — a site can fail on that alone, regardless of how well the soil drains. None of this can be judged from a map, which is exactly why the test is required.
What a BRE365 test involves
The method is set out in BRE Digest 365, and it is more involved than most people expect. It is not a single hole and a stopwatch.
- Trial pits are excavated where the soakaway is proposed and taken down below its intended base. How many depends on the size of the site and what the drainage design needs.
- Each pit is filled to at least 75% of its effective storage depth before timing begins.
- Each pit is then filled and timed three separate times, recording how long the water takes to fall between 75% and 25% of the effective storage depth. Three fills per pit is what BRE365 asks for, and it is what we do.
- The slowest result is used to calculate the infiltration rate, so the design is based on the worst case rather than a flattering one.
Because each pit is tested three times and pits have to drain fully in between, a proper BRE365 test is not a one-hour job. We plan for that, and we would rather tell you a site is unsuitable than hand over a number that will not survive scrutiny at the planning stage.
Planning conditions in Stafford
Stafford Borough Council routinely attaches drainage conditions to permissions, particularly for rural plots, barn conversions and self-builds outside the reach of a mains surface water sewer. The condition usually asks for infiltration testing to BRE365 and a soakaway design based on the results, submitted for approval before work starts.
It is worth testing early. If infiltration turns out not to be viable, the drainage strategy has to change — attenuation, a discharge to a watercourse, or a different layout — and finding that out after the groundworks are priced is an expensive surprise.
Foul drainage and septic tanks
If the site is not on mains foul drainage, that is a separate test. Drainage fields for septic tanks and package treatment plants are sized using the method in BS 6297, referenced by Part H of the Building Regulations, and the figure it produces is not interchangeable with a BRE365 result. Plenty of rural sites around Stafford need both, and we can carry them out on the same visit.
Work we have done near Stafford
We have carried out 44 tests within fifteen miles of Stafford, and 152 within twenty-five miles, so the ground around the town is familiar to us. Recent work in the area has covered self-build plots, agricultural buildings being converted, and extensions where the existing surface water arrangement was no longer adequate.
What you receive
- A full report with the recorded times for every pit and every fill
- The calculated infiltration rate, ready to hand to your engineer or planner
- Trial pit locations and depths
- Photographs of the testing on site
- A clear statement of whether a soakaway is viable, and if not, why not
Areas we cover around Stafford
We test across Stafford town, Stone, Eccleshall, Gnosall, Penkridge, Haughton, Weston and the surrounding villages. Testing is available Monday to Friday, and we will always try to work around your groundworker’s programme.
Get a quote
Contact us for a free, no-obligation quote for percolation or infiltration testing anywhere in Stafford. Tell us the postcode and roughly what is proposed. We reply to enquiries within 24 hours, and ask that you allow up to 48 hours for a fee proposal. Call 01902 475653 or request a quote online.
Percolation testing around Stafford
Each dot is a site we have tested. 13 within ten miles of Stafford, 123 within twenty-five.
Also serving Staffordshire
This page is part of our coverage across Staffordshire, which also includes:
Recent work near Stafford
