Terms for RRain downpipe / downspout
Receiving water courses
Replenishing / system control
Roof runoff water
A retention cistern is used for rainwater retention. Combined solutions (e. g. GRAF Retention Cistern Plus) combine rainwater retention with rainwater use. The water level may rise up to the emergency overflow and slowly fall after rain to the long-term maximum water level. The remaining rainwater is available for use.