Rainwater drainage is the whole system of gutters, outlets and pipes that collects rainwater from roofs and paved surfaces and carries it away in a controlled way. The aim is to lead the water away from the building and foundation quickly and without damage.
Parts of the system
- Gutter — collects the water along the roof edge
- Outlet and hopper — connect the gutter and downpipe
- Downpipe — carries the water vertically downwards
- Underground drain — transports the water below ground to the discharge point
Where does the water go?
In the past, all rainwater went into the combined sewer. Today it is separated as much as possible:
- Infiltration — the water soaks into the ground via a soakaway crate or gravel bed
- Surface water — discharge into a ditch, pond or canal
- Separate sewer — a dedicated rainwater pipe alongside the foul-water drain
Application and points of attention
- Sizing — the drainage capacity is matched to the roof area and rainfall intensity
- Emergency overflow — on flat roofs, an overflow prevents the water from standing too high
- Climate adaptation — with heavier downpours, infiltration on the plot is increasingly chosen
- Leaf guard — a leaf grid prevents blockages
Related terms
- Gutter
- Downpipe
- Infiltration
- Separate sewer
- Emergency drain
- Blue roof
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