Infiltration Half Drain time calculations

We have recently been challenged by Wiltshire LLFA regarding half drain times.

As I understand it, Flow calculates the half drain time to CIRIA 156 which gives a significantly longer half drain time than the BRE365 method that Micro Drainage uses. As the infiltration tests are typically carried out using BRE365, the LLFA are getting confused with their requests. Therefore, it would make sense to have the option of which method Flow uses to calculate the half drain time to better reflect the original testing methodology. It is also essential to have the half drain time to be a printable option for the results.

This is a crucial issue for us now and going forward on other schemes with infiltration features.