For the facilities in the wet pond box and biofilter box, the functions for calculating the impact of precipitation on the required flow detention volume have been revised, which only gives a marginal calculated flow detention volume for normal-sized facilities. However, the effect can be seen within the value figures shown for slightly larger to much larger facilities per reduced catchment area, where the facility surface occupies a larger part of the catchment area than normal.

The same dimensioning flow as before (Qdim) is reported in the facility images, i.e. the flow from direct precipitation (Qp) is not shown there. The latter flow is not shown (for the time being in any case) because it is different in size for different rain durations, but it is thus included in the calculation of the required detention volume. The treatment effect and the calculated concentration and load of pollutants after treatment are not affected by these revised functions.