Do I Need a BRE365 Soakaway Test Before Submitting Planning?
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 only recognised method of demonstrating that a soakaway is suitable is by carrying out infiltration testing 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:
New dwellings;
House extensions;
Commercial developments;
Schools;
Care homes
Industrial units;
Barn conversions;
Caravan parks; and
Replacement dwellings.
It is commonly requested where developers propose:
Soakaways;
Infiltration basins;
Permeable paving;
Swales;
Rain gardens; and
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:
the soakaway will drain properly
groundwater levels are too high
clay soils will prevent infiltration
groundwater could become polluted.
Planning officers therefore require evidence rather than assumptions.
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:
the soakaway will drain properly
groundwater levels are too high
clay soils will prevent infiltration
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:
Groundwater monitoring;
Hydrogeological Risk Assessments;
Flood Risk Assessments;
Drainage strategies; and
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.
