If you’re planning to build a new home, extension, commercial development or change of use, there’s a good chance your Local Planning Authority will ask whether surface water can be managed using soakaways.
The method planning authorities and Lead Local Flood Authorities expect to see is infiltration testing carried out in accordance with BRE365.
At H2Ogeo Ltd we regularly undertake BRE365 soakaway testing throughout the South East helping developers, architects and homeowners discharge planning conditions quickly and confidently.
What is a BRE365 Soakaway Test?
A BRE365 soakaway test measures how quickly water infiltrates into the ground.
The test provides an infiltration rate used to design soakaways capable of storing rainfall during storm events.
Unlike simple percolation tests, BRE365 follows a recognised methodology that has become the industry standard across the UK.
Most planning authorities expect soakaway testing to be completed before approving infiltration drainage systems.
When is a BRE365 Test Required?
You may require testing if your development includes:
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New dwellings;
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House extensions;
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Commercial developments;
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Schools;
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Care homes
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Industrial units;
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Barn conversions;
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Caravan parks; and
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Replacement dwellings.
It is commonly requested where developers propose:
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Soakaways;
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Infiltration basins;
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Permeable paving;
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Swales;
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Rain gardens; and
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Infiltration trenches.
Why Planning Authorities Request Testing
National planning policy encourages Sustainable Drainage Systems (SuDS) wherever practical.
However, infiltration drainage can only be used where the underlying ground is suitable.
Without testing, nobody knows whether:
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the soakaway will drain properly
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groundwater levels are too high
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clay soils will prevent infiltration
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groundwater could become polluted.
Planning officers therefore require evidence rather than assumptions.
Can You Use a Neighbour’s Test Results?
Usually not.
Although neighbouring sites may appear similar, geology can vary considerably across relatively short distances.
Local Planning Authorities generally expect testing to be undertaken on the development site unless there is robust evidence demonstrating that ground conditions are effectively identical.
Site-specific testing remains the most reliable approach.
Why Early Testing Saves Money
One of the most common causes of planning delays is discovering drainage constraints after permission has been granted.
Early testing allows drainage strategies to be designed correctly from the outset.
It can also identify whether alternative drainage solutions should be considered before detailed design begins.
Why Choose H2Ogeo Ltd?
Unlike many drainage consultants, H2Ogeo is led by an experienced hydrogeologist.
That means we don’t simply carry out infiltration tests.
We interpret the underlying geology, groundwater conditions and hydrogeological setting to provide technically robust advice.
Our reports are prepared specifically to support planning submissions and planning condition discharge.
We also offer:
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Hydrogeological Risk Assessments;
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Flood Risk Assessments;
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Drainage strategies; and
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Nutrient neutrality assessments.
Need a BRE365 Soakaway Test?
Whether you’re a homeowner, architect, planning consultant or developer, H2Ogeo Ltd provides practical, science-led advice backed by over 20 years of hydrogeological experience.
We undertake BRE365 soakaway testing across Sussex, Surrey, Hampshire and Kent and provide planning-ready reports with rapid turnaround times.
Get in touch today to discuss your project and avoid unnecessary planning delays.
Common questions
What is a BRE365 Soakaway Test?
A BRE365 soakaway test measures how quickly water infiltrates into the ground. It provides an infiltration rate used to design soakaways capable of storing rainfall during storm events, following a recognised methodology that has become the industry standard across the UK.
When is a BRE365 test required?
You may require testing if your development includes new dwellings, house extensions, commercial developments, schools, care homes, industrial units, barn conversions, caravan parks or replacement dwellings — commonly where developers propose soakaways, infiltration basins, permeable paving, swales, rain gardens or infiltration trenches.
Can you use a neighbour's test results instead of testing your own site?
Usually not. Although neighbouring sites may appear similar, geology can vary considerably across relatively short distances, so Local Planning Authorities generally expect testing to be undertaken on the development site itself unless there is robust evidence that ground conditions are effectively identical.
Why does early testing save money?
One of the most common causes of planning delays is discovering drainage constraints after permission has been granted. Early testing allows drainage strategies to be designed correctly from the outset, and can identify whether alternative drainage solutions should be considered before detailed design begins.