With any conventional gravity flow drainage, the main sewer pipe can become overloaded due to increased flow when the water level on the roof rises above the water level planned for the main drainage design.

For example, when the emergency drainage is in operation, the water level at the main drain reaches 75 mm instead of 35 mm, which according to the flow curve typically leads to an increased flow into the main sewer pipe.

Throttled main drainage

To prevent overloading the main sewer pipe even at this higher water level, the flow in the overload-free main drainage system (similar to retention) is throttled by a throttle pipe with project-specifically calculated openings.

Areas of application

Densely built residential areas with undersized main sewer pipes, new buildings between existing buildings with a shared main sewer pipe, increased rainfall intensity.