Shells purify rainwater

In Wetteren in East Flanders, Aquafin has set up a pilot project with an innovative technique for purifying and recycling rainwater. With Urban Rainshell, washed seashells and minerals do the purification work.


Urban Rainshell is a system patented by the Dutch EWB. In Wetteren the system was installed under a playground. Rainwater is buffered and purified using natural, renewable and circular materials: washed seashells and minerals. The treatment ensures that the rainwater can be used safely.

Water for playing

“In Wetteren we connected the rainwater from the shopping area behind the playground, mainly from car parks, drives and roofs, to the sewer,” says Birgit De Bock, study manager at Aquafin. “Then it’s connected to a supply manifold drain to the shell buffer with a mix of shells and minerals. The surplus rainwater overflows into a soakaway basin where it can enter the soil and overflow into the rainwater drain in case of heavy rainfall. The treated rainwater is used as play water for children in the playground. We also provide a hand pump so that the rainwater can be efficiently recycled for use on the allotments next to the playground and local residents’ gardens. If the research results are favourable, a second pump can eventually be connected so that the allotments can make better use of this rainwater stock.”

International pilots

In this pilot project – TKI Circular Rain – Aquafin researches together with water research institute KWR how far this innovation enables heavy rainfall to be stored and treated for safe recycling as extinguishing, irrigation, play or process water. Some 15 partners work together in various pilots in the Netherlands and Belgium. The project is partially funded by the Dutch Ministry of Economic Affairs’ Allowance for Top Consortia for Knowledge and Innovation (TKIs).