The TOPAS domestic WWTP guarantees operation even after an interruption of sewage inflow for up to 6 months. Thanks to the control system which can effectively optimize the reduction of aeration when the inflow is interrupted and also by supplying nutrients to the bacteria by recirculating the remaining water in the WWTP it retains its wastewater treatment function even after 6 months without inflow. This unique solution has been tested by the SZÚ Testing Institute in Brno with excellent results and is therefore ideally suited for recreational operation in cottages.