Some woven and nonwoven geotextiles exhibit a resistance to water penetration at initial wetting. This phenomenon is known as ‘Water Head Support’. Tests have been carried out to investigate whether the wetting problem is only an initial problem and whether geotextiles behave in the same way in contact with soil. Therefore drain tubes were wrapped with geotextiles and installed in a sand model. Tests were carried out under various soil conditions (dry and wet) and geotextile conditions (dry and wet).

This resistance to water penetration influences the performance of the geotextile and is disadvantageous compared with geotextiles which do not possess this resistance.

The apparatus described to evaluate the initial resistance to water penetration applies a water head to the geotextile. Tests were carried out for a number of geotextiles. The results revealed that, for some geotextiles, substantially high water heads are reached before the water starts to flow through the geotextile.