It is recommended to fit a suitable, upstream rainwater filter that prevents dirt from entering the system. In the case of a retention cistern (combined rainwater retention and harvesting), this is also needed to safeguard high water quality.
GRAF retention cisterns for retaining rainwater and relieving the strain on the public sewer network can be sized for virtually any capacity.
A detention cistern collects rainwater and discharges it through a flow control into the sewer system after a controlled period of time.
Retention with Storage Modules
Retention capacities can also be realised with storage modules, welded in a waterproof plastic liner.
Lifting Choke Shaft
The lifting choke shaft is made up of the choke shaft and the lifting pump set. A lifting choke shaft can be implemented if the storage tank is located below the sewer. The pump located in the shaft will convey the water at a predesigned flow to the desired location. The lifting pump set can be combined universally with all available retention tanks, e.g. Platin flat tank, Carat or Carat XL underground tank, etc.