Percolation Tests carries out BRE365 soakaway percolation testing and foul infiltration testing across Congleton and the surrounding East Cheshire area.
We are based in Wolverhampton, about 40 miles away, and Congleton is well inside the area we cover as standard. We have carried out 27 tests within twenty-five miles of Congleton.
Ground conditions in Congleton
Congleton sits where the Cheshire Plain meets the Pennine foothills, giving the town a mix of glacial clay in the lower ground along the River Dane and firmer, better-draining ground on the higher land towards the moors. This transition means percolation rates can vary meaningfully depending on a site’s exact position within the district.
The Cheshire Plain carries some of the thickest glacial till in the country, and around Congleton that boulder clay is often the deciding factor rather than the rock beneath it. Till drains poorly and can be many metres deep, so a good result usually depends on finding a sand or gravel lens within it. Those lenses are unpredictable across a single field, which is exactly why a site-specific test is required rather than an assumed rate for the area.
What we test for
- BRE365 percolation testing for surface water soakaway design
- Foul effluent infiltration testing (Part H) for septic tanks and treatment plants
- Drainage strategy support for planning submissions
How the test is carried out
BRE Digest 365 sets out the procedure, and it is more demanding than it sounds. A single filling of a single hole proves very little.
- Trial pits are excavated at the proposed soakaway position, taken down below the level the soakaway will sit at. The number depends on the site and the design.
- Each pit is filled to at least 75% of its effective storage depth, which is where the timed measurement starts from.
- Each pit is then filled and timed three times over, measuring the fall from 75% to 25% of the effective depth.
- The slowest of those runs is carried into the calculation, which keeps the resulting design conservative.
The three fills and the draining time between them are why this cannot be rushed. A number produced quickly is a number that tends to get challenged.
Planning conditions in Congleton
Applications in the Congleton area are dealt with by Cheshire East Council, and drainage conditions are attached routinely — particularly on rural plots, barn conversions and self-builds with no mains surface water connection. The condition normally asks for infiltration testing to BRE365 and a soakaway design based on the result, approved before work starts.
Testing early is worth the trouble. If infiltration turns out not to be viable the drainage strategy has to change, and discovering that after the groundworks are priced is an expensive surprise.
Septic tanks and foul drainage
Surface water and foul drainage are tested differently, and the results are not interchangeable. A drainage field for a septic tank or treatment plant is sized using BS 6297, which Part H of the Building Regulations refers to. If your site near Congleton needs both a soakaway and a drainage field, we can carry out both tests in one visit rather than two.
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
Coverage
We test across Congleton, Sandbach, Biddulph, and the surrounding villages. Available Monday to Friday.
Get a quote
Contact us for a free, no-obligation quote for percolation or infiltration testing anywhere in Congleton. Call 01902 475653 or request a quote online.
Nearby areas we cover
Recent work near Congleton
Percolation testing around Congleton
Each dot is a site we have tested. 24 within twenty-five miles of Congleton.