Individual and other Appropriate Systems (IAS) are waste water treatment systems for one or a few households. They are authorised in certain circumstances under the Urban Waste Water Treatment Directive (UWWTD) and especially when it would be disproportionally expensive to build a sewer network to connect the waste water to a WWTP in a rural area. As the evaluation of the UWWTD revealed, IAS is one of the remaining sources of pollution in urban waters and often because of the lack of control and maintenance over them. However, with a variety of technical solutions, they offer an interesting alternative to municipal collection systems, especially with the European climate neutrality objective for 2050. In this briefing note, we explore how water-related legislation can be improved to ensure that IAS can continue to be part of the available solutions for sustainable waste water management.