Rain Intensity and Roof Size
The percentage of rainfall WISY-Filters are collecting (which is their efficiency) is depending on the amount of water coming through the pipes. During heavy rainfall (with lots of water coming) the efficiency is lower than during a light drizzle. Also the connected roof size has a direct impact on the water amount and thus the efficiency.
90 % of the annual rainfall
All WISY rainwater filters are designed to collect around 90% of the annual rainfall and use 10% to rinse the stainless steel filter insert.
The vast majority of individual rainfall events in the temperate climate zone (e.g. Europe) is rather light. Here, the efficiency of the filters increases to up to 99 %. Heavy thunderstorms have only a very little share of the annual rainfall.