What is waterproofness/water column?

The water column indicates the level of water pressure that a fabric can withstand before water penetrates it. The waterproof specification of a material is generally stated in mmH2O (water column/millimetres).
The higher the water column rating of a material, the greater the water pressure it can withstand and the greater the level of waterproofness.

Our different TEXAPORE performance levels have water column ratings from 1700 to 50,000 mm. For example, when sitting on wet grass in a pair of waterproof pants, the pressure on the fabric corresponds to a water column rating of approx. 2000 mm.
Pressure is almost always measured in mbar (millibars) or Pa (Pascals). However, in the textile industry, using “mmH20” has become commonplace: this convention originates from the time before analogue or digital pressure measurement gauges were available, when the pressure exerted was read off the level of a column of water in a small tube.