Percolation Tests

Subscan perform percolation tests for businesses, developers and contractors as part of ongoing site investigations. A soil percolation test is required to be carried out on the land where the septic tank system or sewage treatment plant soakaway is intended to be built.  It is a test that determines the rate in which soil absorbs a known volume of water.  This is to make sure that the land (soil) is suitable for a soakaway, and to make sure that the soakaway is designed properly.

A percolation test includes:

  • Excavate a hole 1m square and 1m deep
  • Dig the test hole vertically to the proper depth. Remove all loose debris
  • Line with Visqueen
  • Fill the test hole with water
  • Accurately time noting depth at 5, 10 and 30 second increments
  • Carry out the test at least 3 times, with at least 2 trial holes
  • The average figure from the tests is taken
  • Report produced

Industry experts on hand

Using the latest technology and equipment to perform percolation tests we can quickly identify any issues on site. Our highly qualified engineers use state-of-the-art equipment to deliver highly accurate data to assess whether a site is safe where a septic tank or sewage treatment plant soakaway is intended to be built. At Subscan we put the safety of your site first.

Want to find out more?

For more information or to receive a site specific quotation please contact us on 0344 499 5220 or at

Case Study

Construction Marine Ltd

Project type:
CCTV survey and desilting

Various sites over the UK


As part of an ongoing maintenance contract for Network Rail, Subscan ensure that all drainage solutions along the East coast railways from London to Newcastle are maintained.

Subscan have been appointed by Construction Marine Ltd to work on a project for Network Rail sites and structures as part of an ongoing project of a number of years.


To ensure that the drainage solutions along the East Coast railway from London to Newcastle are maintained, Subscan are tasked to carry out CCTV condition surveys and desilting of culverts along the route.

Some of the work locations are very rural and inaccessible but our fleet of off-road units makes the tasks easier to complete. We have a 100% success rate with CML on all projects we carry out and ensure all project are completed on time, with no impact on train schedules.

Client Testimonial

“The Subscan UDS team of surveyors and drainage engineers helped our minor works team out again and did a thoroughly professional job. We will continue to work with Subscan on LNE projects throughout the region.”

Lee Sanderson, Building & Civils Project Manager, Construction Marine Ltd