Control for regulating rain-water drainage - comprises reservoirs which store water for short term when drains overflow

摘要

The control is for regulating the drainage of rainwater and comprises reservoirs, the level in which varies according to the severity of the rainfall. The reservoirs admit water from the surface to be drained via ducts (B) and discharge into a main drain below via narrower outlets (E). A valve (F) allows water to be stored for a short-term in each reservoir until the main drain is able to take the flow. This allows the main drain to be constructed with a smaller diameter than usual.