Percolation Tests provides BRE365 soakaway percolation testing and foul infiltration testing across Nantwich and the surrounding South Cheshire countryside.
We are based in Wolverhampton, about 37 miles away, and Nantwich is well inside the area we cover as standard. We have carried out 17 tests within fifteen miles of Nantwich and 63 within twenty-five, so the ground around the town is familiar to us.
Ground conditions in Nantwich
Nantwich sits on glacial boulder clay and sand deposits typical of the Cheshire Plain, with drainage performance varying between the heavier clay areas and the sandier glacial outwash found in patches across the district. The area’s historic salt and brine extraction has also left some ground disturbance locally, another reason to test on site rather than assume.
The Cheshire Plain carries some of the thickest glacial till in the country, and around Nantwich 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 Nantwich
Applications in the Nantwich 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 Nantwich 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 Nantwich and the surrounding rural South Cheshire villages. Available Monday to Friday.
Get a quote
Contact us for a free, no-obligation quote for percolation or infiltration testing anywhere in Nantwich. Call 01902 475653 or request a quote online.
Nearby areas we cover
Recent work near Nantwich
Percolation testing around Nantwich
Each dot is a site we have tested. 6 within ten miles of Nantwich, 58 within twenty-five.