Percolation Testing in Shropshire

Percolation Tests carries out BRE365 percolation and foul infiltration testing throughout Shropshire, supporting planning applications and off-mains drainage design for rural sites, self-builds, and developments.

Ground conditions in Shropshire

Shropshire has some of the most geologically varied ground in the West Midlands. The county includes areas of sandstone around Shrewsbury and the north, which typically percolate well, alongside heavier clay soils in parts of the south and around the Shropshire Hills. The Shropshire Meres and Mosses area in the north-west, a wetland landscape formed by glacial deposits, often presents slow-draining, high water table ground that needs particularly careful testing before any soakaway is designed. Given this range, a site-specific percolation test is essential — Shropshire is not a county where ground conditions can be assumed from a postcode alone.

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

Coverage across Shropshire

We regularly test across Shrewsbury, Telford, Oswestry, Market Drayton, Bridgnorth, Ludlow, Whitchurch, and the wider rural county, including sites in the Shropshire Hills Area of Outstanding Natural Beauty. Testing is available Monday to Friday, and rural self-builds with tight timescales are a large part of what we do.

Why get a percolation test

Many rural Shropshire plots rely on private drainage rather than mains connections, making a BRE365 percolation test a routine planning requirement. Testing early avoids delays to discharging conditions and helps size your drainage field or soakaway correctly first time.

Planning authorities in Shropshire

Drainage conditions on Shropshire planning permissions are set by the district or unitary council, and for larger schemes the Lead Local Flood Authority is consulted on the surface water strategy. Both expect infiltration to be considered first in the SuDS hierarchy and both expect the evidence to be a BRE Digest 365 test carried out on the site, not a figure taken from a map or a neighbour’s result. The authorities we most often write reports for in Shropshire are:

• Shropshire Council — the unitary authority for the whole county outside Telford, and also the Lead Local Flood Authority
• Telford & Wrekin Council — unitary authority and Lead Local Flood Authority for Telford, Wellington, Newport and the surrounding parishes

If your decision notice asks for ‘infiltration testing in accordance with BRE 365’, ‘evidence of soakaway feasibility’ or ‘percolation test results to BS 6297’, that is what we produce, laid out so the case officer can find what they need without asking again.

Ground conditions in more detail

The practical split is north and south. North of Shrewsbury the Permo-Triassic sandstones can take water well, but they are blanketed over large areas by glacial till and by the peat and lake clays of the Meres and Mosses, so a plot near Wem or Whitchurch often behaves nothing like the rock beneath it. The Severn corridor through Shrewsbury and Bridgnorth carries river terrace gravels that drain freely next to alluvial clays that do not. Around Telford, made ground from the old coalfield and ironworks is the usual complication. South of the A458, in the Shropshire Hills and towards Ludlow, the older Silurian mudstones weather to a shallow, slow-draining clay and the ground slopes — which brings the question of where a soakaway’s water ends up, not just how fast it goes in.

Which test does your site need?

A BRE 365 test sizes a surface water soakaway — roof and driveway run-off — and is what Approved Document H3 and the SuDS hierarchy point to. A BS 6297 test sizes a foul drainage field for a septic tank or package treatment plant under Approved Document H2. They use different pits, different procedures and different calculations.

Much of rural Shropshire has no mains foul sewer, so a new dwelling or conversion usually needs a package treatment plant or septic tank with a drainage field. That drainage field is sized from a BS 6297 percolation test, which is a different procedure from BRE 365 and produces a different figure — one will not satisfy a condition asking for the other. Rural sites here frequently need both surface water and foul evidence, and we carry out both tests on one visit.

What our testing in Shropshire shows

We have carried out more than 160 tests within a dozen miles of the Shropshire towns listed below since 2018. Of the sites where we recorded an outcome, roughly two in three did not achieve an infiltration rate that would support a conventional soakaway. That is not a reason to skip the test — it is the reason to do it early. A measured rate, even a poor one, is what your engineer needs to size attenuation or justify a different discharge, and it is what the authority will accept. A guessed rate is what gets a scheme sent back.

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

Get a quote

Contact us for a free, no-obligation quote for percolation or infiltration testing anywhere in Shropshire. Call 01902 475653 or request a quote online.

Towns and areas we cover in Shropshire

• Telford — made ground from the coalfield and ironworks is the usual issue; 47 tests within ten miles
• Shrewsbury — Severn terrace gravels next to alluvial clay, so results change street by street; 43 tests within ten miles
• Bridgnorth — sandstone that often drains well, with pockets of till; 37 tests within ten miles
• Whitchurch — Cheshire Plain boulder clay; success usually means finding a sand lens; 11 tests within ten miles
• Oswestry — till over sandstone and limestone towards the Welsh border; 17 tests within ten miles
• Market Drayton — sandstone ridge east of the Tern, till in the valley; 12 tests within ten miles
• Ludlow — Silurian mudstones weathering to shallow clay on sloping sites; 8 tests within ten miles

Recent work near Shropshire