Manufacturers of such rainwater filters try to counteract this with special flow behaviour or additional spraying devices. However, it is technically only possible to a limited extent to remove the dried dirt. Rainwater filters with inclined or horizontal (i.e. flat) filter mesh basically have the problem that leaves and moss remain on them as soon as the water flows down through the mesh. This means that they become dirty after a very short time. In larger rainwater systems, the rainwater flows through an inlet cleaner into the lower part of the rainwater storage tank. Corrosion-resistant pumps with floating intake filters take over the task of transporting the water to the tapping points in the larger rainwater systems with mostly underground tanks. This type of rainwater system can be found in everything from single-family homes and industrial buildings to sports stadiums.

If, on the other hand, the rainwater is to be taken with a watering can, the rainwater system is largely reduced to a downpipe filter with a preferably frost-proof rain barrel, as well as a tap for water extraction.Only filters with vertical filter mesh are able to remove solids from rainwater without becoming an obstacle themselves in the medium term. With extremely low maintenance, you can keep the filter permanently functional. Vertical or upright filter meshes are the best way to remove dirt reliably and permanently from rainwater. WISY's unique filter principle allows rainwater to be directed sideways through a filter mesh while leaves and moss fall past it. If the dirt load remains in the filter basket for a long time, biological decomposition begins there. Subsequent rain events regularly flush the resulting decomposers and organisms into the cistern water, causing water quality to suffer.

Regardless of whether it is a downpipe filter, an earth filter or a cistern filter, the arrangement of the filter fabric always plays an important role. This determines whether it is actually the filtered rainwater or mainly the dirt that is collected. For example, all rainwater systems have a rainwater filter, which is used to remove coarse dirt, leaves and other particles from the rainwater so that they do not enter the rainwater system's storage tank. Rainwater systems can have a different structure depending on the application. However, they usually share some of the most important components, which vary in size depending on the area of application of the complete rainwater system.