Collection in rainwater tanks
The method
Run-off from roofs and surfaces can be collected in large underground rainwater tanks (2-4 m3) and used for watering gardens and washing cars, etc. The tank is fitted with pumps to pump up water for use as necessary. Overflow from the tank can be channelled to an infiltration area. If infiltration is not an option, the overflow can be channelled to a sewer.
The tank can also be used as an extra storage facility in the event of cloudburst. When a cloudburst is forecast, the tank is drained into the sewage system while the system still has capacity. When the cloudburst occurs the tank is therefore empty, and the storage capacity can be fully utilised to store rainwater from the house.
Figure 1: Rainwater tank with overflow to soakaway.