Nothing else than the height of the liquid column indicating hydrostatic pressure. In the case of aeration and mixing of liquids, the water table means the height of the water column (water pillar) – as the pressure to be overcome for the air stream, e.g. 5 m – as the depth of the aeration tank – for the air entering the sewage from the bottom of the tank through the fine-bubble diffuser, it means overcoming a pressure of approximately 500 mbar