Coverage

Where we work.

We carry out infiltration testing, percolation testing and groundwater monitoring across every county in England and Wales. Distance doesn't change the turnaround — results and a full report still land the day after testing (subject to terms and conditions).

Ground conditions

What the ground tends to do, region by region.

South East & LondonLondon Clay, chalk, Lower Greensand

London Clay dominates the London basin, north Kent and south Essex. It is very low permeability, so infiltration commonly fails and a soakaway is rarely viable — here the test result is most useful as the evidence justifying a connection to the public sewer. Where the chalk of the North Downs and Chilterns surfaces, or the Lower Greensand through Surrey and west Kent, results improve sharply, sometimes within a few hundred metres.

South & South WestChalk downland, Culm Measures, granite

The chalk of the Downs, Salisbury Plain and much of Dorset generally accepts water well, though solution features mean figures can vary noticeably from pit to pit on the same site. Further west, the Culm Measures of north Devon and Cornwall are mudstone-dominated and typically drain poorly, while the weathered granite around Dartmoor and Bodmin depends almost entirely on how deep the weathering runs.

East of EnglandChalk, Breckland sands, fen peat, boulder clay

Chalk beneath Norfolk and Suffolk, and the Breckland sands, often give strong infiltration rates. The Fens of Cambridgeshire and south Lincolnshire are the opposite case: the infiltration figure matters less than the winter water table, which is where groundwater monitoring earns its place. Boulder clay across much of Essex and mid-Suffolk drains slowly.

The MidlandsMercia Mudstone, Sherwood Sandstone, Jurassic limestone

Mercia Mudstone runs through Nottinghamshire, Leicestershire, Staffordshire and Cheshire — low permeability, and one of the most common reasons a test comes back failed. The Sherwood Sandstone belt behaves in the opposite way: free-draining, but a major aquifer, so groundwater protection enters the design. Jurassic limestone along the Lincolnshire Edge and through the Cotswolds drains via fissures, giving rapid but inconsistent results.

Northern EnglandGlacial till, Carboniferous limestone, Coal Measures

Glacial till blankets much of Lancashire, Cheshire and the Vale of York, and generally drains poorly. Carboniferous limestone in the Dales and the Peak can be extremely permeable, with karst features that make placement of the test pit important. Coal Measures across Yorkshire, Derbyshire and Northumberland are mixed, and mining legacy is often a factor in what can be dug and where.

WalesMudstone and slate uplands, Coal Measures, coastal levels

Ordovician and Silurian mudstones and slates across mid and north Wales usually mean thin soils over shallow rockhead, which limits both infiltration and how deep a trial pit can practically go. The South Wales Coalfield valleys are variable, with made ground common. On the coastal plains — the Vale of Glamorgan, the Gwent Levels, Anglesey — conditions differ widely, and on the Levels a high water table tends to govern the design.

These are regional patterns, not predictions

The notes above come from published regional geology. They are useful for anticipating what you are likely to find, and no substitute for testing. Two plots on the same street can return very different figures — which is exactly why BRE 365 requires testing at the proposed soakaway location and depth rather than inferring a rate from a map.

Counties

Every county in England and Wales.

England — 47 counties

  • Bedfordshire
  • Berkshire
  • Bristol
  • Buckinghamshire
  • Cambridgeshire
  • Cheshire
  • Cornwall
  • Cumbria
  • Derbyshire
  • Devon
  • Dorset
  • Durham
  • East Riding of Yorkshire
  • East Sussex
  • Essex
  • Gloucestershire
  • Greater London
  • Greater Manchester
  • Hampshire
  • Herefordshire
  • Hertfordshire
  • Isle of Wight
  • Kent
  • Lancashire
  • Leicestershire
  • Lincolnshire
  • Merseyside
  • Norfolk
  • Northamptonshire
  • Northumberland
  • North Yorkshire
  • Nottinghamshire
  • Oxfordshire
  • Rutland
  • Shropshire
  • Somerset
  • South Yorkshire
  • Staffordshire
  • Suffolk
  • Surrey
  • Tyne and Wear
  • Warwickshire
  • West Midlands
  • West Sussex
  • West Yorkshire
  • Wiltshire
  • Worcestershire

Wales — 22 principal areas

  • Anglesey
  • Blaenau Gwent
  • Bridgend
  • Caerphilly
  • Cardiff
  • Carmarthenshire
  • Ceredigion
  • Conwy
  • Denbighshire
  • Flintshire
  • Gwynedd
  • Merthyr Tydfil
  • Monmouthshire
  • Neath Port Talbot
  • Newport
  • Pembrokeshire
  • Powys
  • Rhondda Cynon Taf
  • Swansea
  • Torfaen
  • Vale of Glamorgan
  • Wrexham
Working away from base

How distance is handled.

Testing is mobilised from West Oxfordshire, and sites further afield are grouped where we can so travel doesn't land on a single job. In practice that affects when we can get to you, not what you receive — the testing method, the reporting standard and the next-day turnaround are the same wherever the site is.

For sites at distance it's worth sending plans early. Desk-study research and BGS records are done before we travel, so the visit is a single, properly planned trip rather than a return journey.

Auger rig set up for infiltration testing on a hillside site with open countryside behind