At the Engelthal Abbey of the Benedictines, in the Altenstadt district of the Wetterau region in Hesse, it was the technical director of the abbey who was the driving force behind the utilisation of rainwater. Outside of work he is also a strong promoter of protection for the environment. There was no state funding in Engelthal; however the parish supports the rainwater concept.
Water is drained from a roof area of 1,200 m² plus connecting structures, the guesthouse and church. The rainwater flows along distances up to 70 m through underground concrete pipes to the filter. 25 m further up is the rainwater storage tank, which has a capacity of up to 13 m³. This is where a double-pump unit fitted with an automatic control systems takes water for flushing 50 toilets. The heart of the system is a WFF 300 vortex fine filter by WISY AG. Thanks to the filter unit in the feed pipe to the storage tank, dirt particles up to a fineness of 0.38 mm are filtered off to the drain system.