The article presents the results of the viability economic analysis of the use of an installa- tion for the treatment of greywater and/or rainwater, in order to reuse the recovered water for flushing toilets and watering the garden. The economic indicator in the form of simple payback time (SPBT) was used in the analysis. The use of a dual water supply system should theoretically reduce costs for water supply and sewage disposal, ensuring investment profitability. The analysis was carried out assuming the possibility of using water recovery from only greywater. only rainwater or from greywater and rainwater in a single household inhabited by 4 people. It was also assumed that the building could be connected to the water supply and sewage network or only to the water supply network and the sewage tank. Based on the results of the analysis it showed that the cost of the water supply and sewage disposal is crucial to the profitability of using the water recovery system in a single household. For prices above 12 PLN/m3. water recovery should be considered.