About non-return valves

Non-return valves allow water to pass whenever the upstream pressure exceeds the downstream one. If the situation is reversed for any reason, the non-return valve will close immediately to prevent backflow.

These devices are usually placed in delivery pipes of pumps and pumping stations, or in bypass pipes, and sometimes in the distribution network as well.

The initial assumption during the modelling process is that the non-return valve is open. If a back-flow occurs, the non-return valve will be closed down in the next timestep.