Water in the soil

Drawing away surplus water from the soil is the essential task of drainage systems. The drainage pipes are selection and installed depending on the capacity of the soil to retain water. But water is not just water – in the soil structure, you have to distinguish between groundwater, backwater and retained water:

Groundwater
The groundwater in the upper soil strata is not always at the same depth, but instead recedes on an annual basis and depending on weather conditions.

Backwater
Backwater is free-moving water that is backed up by an obstruction. It is different from ground water because it comes about only after very heavy rainfall – depending on the amount of precipitation. Backwater thus only exists temporarily.

Retained water
Retained water is mostly bound water that is sometimes also capillary water (e.g. in a bed of clay). Supersaturation can also cause the appearance of surface water.