This paper presents the Herewater, which is an invention that cleans undrinkable water into drinking water with very low energy demand. It uses evaporation followed by condensation. The latent heat released during condensation is recycled back to the evaporation basin in an innovative way. It’s efficiency depends ultimately on the thermic isolation of the device towards the outside. The remains from the undrinkable water are dry so easy to handle. 

Based on a one square meter basin, it follows from a thermodynamic analysis that the Herewater produces 340 litres each 24 hours by 1kW, which can entirely be solar energy. It is easy to add other energy sources to be used when needed.

The equipment is not expensive and contains no moving parts except a fan and a water pump, which together require less than 45 W. The Herewater can be thought of as a hybrid of a solar still and a large facility. Adding a little external energy gives a lot more water because of the way the Herewater is designed.

If many households use recycled own wastewater, both groundwater use and sewage facilities will be relaxed.

Patent is pending for the Herewater, and a prototype is under construction.