Percolation Tests

What is a percolation test?

Soakaway systems can be used to take the wastewater from either a septic tank or a sewage treatment plant. Its a network of perforated or slotted pipework which allows the waste water to percolate safely through the ground without causing pollution.

A percolation test is used to decide whether the soil at a property is suitable for a soakaway system (also known as a drainage field). If the ground is suitable, a percolation test will then decide how big a soakaway system needs to be.

The percolation test itself involves digging three test pits in the area of ground where you are planning to install a soakaway system, and measuring the speed at which the water drains out of the pits. The test is usually carried out over two days.

Here’s a picture of a test pit for a percolation test our team have recently undertaken. You’ll notice the measuring stick that has been used, which helps the engineer to time the speed at which the water drains (or percolates) away.

Read more about what’s involved in a percolation test and how it’s undertaken.

Do I need a percolation test?

If you are thinking about installing a new soakaway system or replacing an existing one, then the simple answer is yes. If a soakaway system or drainage field is installed in ground which isn’t suitable, or if its not the right size to take the wastewater from the property connected to it, then you’re likely to get soakaway problems quite quickly.

The UKDP team can manage everything for you – from undertaking the test itself, through to producing a detailed report outlining exactly how the soakaway system should be constructed. Of course, we can then install the soakaway for you.

What if a percolation test fails?

A percolation test provides a Vp reading, which measures the speed at which water drains into the ground through the test pits. In order for the ground to be considered suitable, the reading must be between 15 and 100. Sometimes, percolation tests can fail right from the start, or it might be that the reading sits outside of this acceptable level. If this happens, our team will work to undertake a thorough assessment of all the options available to you.

Here is an example of a site diagram we have recently created showing the required soakaway construction after percolation tests were completed:

0800 028 9903