WP4C Water Potential Meter

This piece of equipment can be used to measure the suction/water potential of materials.


The most common materials are soil and plant matter but almost any porous material or liquid can be measured.

The instrument works via vapour equilibrium in a sealed chamber. At equilibrium, the relative humidity of the air is measured using the chilled mirror technique, which measures the air and mirror temperature at the point when dew starts to form on a cooled mirror inside the chamber.

The relative humidity of the air in equilibrium with the material is then converted into suction/water potential using classical thermodynamic relationship.

Access arrangements

We can test your samples and provide a file of the gathered data. Those wishing to carry out the measurement themselves can be given access following proper technical and health and safety training.