WaReg protects homes from flooding in Sweden

The problem

As part of routine maintenance, the Backaryd Water Treatment Plant regularly backwashes its filters. During this process, water is discharged into the town's sewer network at a rate of 16 l/s. However, the sewer network can handle a maximum flow of only 5 l/s, so when it receives 16 l/s during backwashing, it becomes problematic for downstream residents. As a result, homes in the downstream area experience sewer backflows into their basements through toilets, showers, and floor drains. There are a few different methods to resolve this issue. One option is to increase the pipe size to accommodate the flow. However, this is an expensive solution for a town of 400 people. A more effective and less resource-intensive solution is to control the flow, attenuate the excess, and only release what the downstream pipes can handle.