Graf offers you the best made of plastic material for your home and industry! As European market leader in the range of rainwater harvesting, we find solutions and inform you on options around the responsible use of water.
A detention cistern retains the rainwater
and drains it into the sewer at a
GRAF cistern for rainwater detention
and sewer relief.
To guarantee retention
of rainwater, a delayed drain is fitted
in the sewer with a delay of 0.05 to 16
l/sec. depending on the customer’s
In the event of heavy
rainfall, the water level in the cistern
rises above this level and is drained
into the sewer at a delayed speed using
a floating drain choke. This relieves the
sewer and the treatment works. The
water level can rise to the emergency
overflow and sink slowly back down
again after the rain.
Sizes between 1,500 – 7,500 l with corresponding retention volumes are possible.
We also construct and supply individual, special solutions.