Water is always needed. In a workshop and a treatment plant too. A grass-covered roof was opted for on the treatment plant.This roof collects the rainwater and stores it. Draining the rainwater is no longer necessary. The water is, as it were, sucked up and used uniformly by the grass. Only when there are extreme amounts of rain is a drain sometimes necessary. The surplus rainwater from the solar power station is drained away to a storage tank and used as grey water for the toilets. By using toilets with two flushing systems, more than 20 litres of water are saved per day and per employee.

Ultra-filtration
During the production of drinking water, certain substances have to be abstracted from the groundwater In Annen treatment plant, this is chiefly iron.Through aeration the iron becomes insoluble and flocculates. These floccules are removed in a sand filter. After filtering the water for some hours, the filter becomes blocked and has to be cleaned. This is done by flushing the filter with drinking water. This flushing releases water contaminated with iron. About 2% of the water made by the treatment plant is needed to flush the filters. This water is purified again in a separate, small purification plant using ultra-filtration and is then disinfected with ultra-violet light.
It is subsequently pumped into the clean-water storage. The sludge is transported to the brickworks in tankers at a rate of approx. 1 tanker per week. Per year 1000 m3 sludge is released in this way.