Use of treated greywater for climate-friendly and resilient urban green spaces and stable groundwater resources

Given falling groundwater levels and rising demand, using drinking water alone to irrigate green spaces is not sustainable. The GRAUfürGRÜN-BLAU project is investigating the use of treated gray water from residential buildings for irrigating public green spaces and for groundwater recharge. At two locations in Vienna (Kauergasse 2 and Pogrelzstraße 8), the quantity, quality, and utilization potential of the gray water produced are being measured. The aim is to develop technical, legal, and organizational solutions for the provision of treated gray water at the interface between private buildings and public green spaces. Ecological risks such as pollutant input and microplastics are also being analyzed, and filter solutions for infiltration are being tested. In addition, an economic evaluation, an analysis of acceptance by the population and administration, and barrier-free processing of the project results are being carried out. The project contributes to resilient, climate-adapted cities and offers replication potential for municipalities with comparable supply structures. The aim is to ensure the availability and performance of urban GI even under future climate conditions – without having to resort to valuable drinking water.