Understanding water table and basements
We find that ‘water table’ is often mentioned where issues of water penetration affect basements & cellars, however the theory in many cases may not be well understood. The intention of this article therefore, is to comment upon the basic theory and background to water table and some of the implications that this has on basement and waterproofing design.
By James Hockey
Defining water table
There is a distinction between what is referred to as ‘perched' water table, versus what we refer to as 'true' water table.
Perched water table is defined within the 2022 revision of British Standard 8102 protection of below ground structures against water ingress, as a ‘reservoir of water in the ground maintained temporarily or permanently above the standing water level in the ground below it, caused by the presence of an impervious soil or stratum of low permeability’.
Or in other words, water may stand (perch) in the ground at a level, before draining down to true ‘water table’, which may be at a much lower level.
