Intense showers are often short and local, and they only cause full-flowing pipes in some places, and for a short time. The solution is therefore retaining the excess water in other places of the system during the relevant time interval. That is - where there is room for it - utilizing those places for storage.
The solution functions in far most precipitation situations and it does not require any investments in larger pipes or in basins, it only requires flow control with suitable flow regulators.
By effective flow control we mean a discharge which quickly reaches the maximum flow and stays at or below this value. This is the flow which there is room for without any problems after the flow regulator, further down in the system.
Generally speaking, the purpose of a flow regulator is protecting the low-lying parts of the sewage system (downstream) against overloading and flooding. A specific quality
of the flow regulator is that it allows liquid to pass further down in the sewage system at a predetermined maximum amount per time unit, regardless the variation in feed flow and regardless the water level immediately before the regulator. See figure 3.
To avoid the risk of blockage and to minimize the need for service and maintenance, the regulator should be without moving parts. Furthermore, its passageway should be large to minimize its resistance in normal, daily runoff situations, and to avoid blockages.