Percolation Test Results Explained: A Chichester Example
2 min readChichesterBy AA Drainage
A percolation test report can look like a page of numbers. Here is a simple explanation of what it tells you.
The percolation value
The test produces an average time for water to drop a set distance in the test holes. This value shows how quickly the soil absorbs water.
What different results mean
Broadly speaking:
- Very fast results may need care to protect groundwater
- Moderate results suit standard drainage fields
- Slow results need larger systems or alternatives
- Very slow results usually rule out a drainage field
Local variation
Around Chichester, soils range from brickearth and gravels to clay. Two gardens in the same village can give very different results, which is why site testing matters.
Frequently asked questions
Can I re-test if results are poor?
You can test in a different location on the plot, which sometimes gives better results.
Does the report go to Building Control?
Yes, it is usually submitted with your drainage design.