**5. Conclusions**

At the moment, the scale of rainwater reuse is still small in Poland, therefore the issue of sustainable rainwater management is highly relevant and an object of active technical debate. The most popular, relatively simple, solution is to adopt small retention/infiltration devices for single development units, allowing increased use/infiltration of rainwater. As shown, this could bring significant environmental and financial advantages to the community and property owners. The economic sustainability of these measures is strictly correlated to the existence of fiscal/fee incentives, although those solutions that contemplate local reuse also benefit from lower public water purchase costs.

Alternative rainwater management solutions aim primarily at relief and possible replacement of traditional sewage systems: as shown, raingarden is a cost-effective and resilient approach, that provide a number of advantages for facility managers interested in sustainability, but its financial viability is limited by the lack of reuse options. Onsite rainwater storage (harvesting) for reuse implies direct financial savings on water supply costs that could make the solution appealing for individual users even in the short term.

Although the generalized use of these systems would add resiliency to stressed water supply networks, additional aspects such as longer flow residence times in distribution systems and resulting quality issues that may arise should be evaluated and addressed.

**Author Contributions:** J.B.-Z. followed field applications and gathered related data. A.G.C. designed the initial manuscript framework and organization. Both authors equally contributed to data interpretation and manuscript preparation. Both authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.
