At Evides, an open connection between the Delft and Westland supply areas was rapidly detected. “We observed a water balance in Westland that we couldn’t explain,” says Henk de Kater of Evides. “Using the CFPD method, we noticed that in one area there was a ‘plus’, while in the other there was a ‘minus’. We studied the situation and it turned out that there was an open boundary-valve, so that water was being transferred from one area to the other. Such situations can easily remain unnoticed and disturb the water balance, but the new method brought it quickly to our attention." The CFPD method is quick and simple. It uses measurement data exclusively and is therefore independent of assumptions or uncertainties, which are typical of many models. Thanks to CFPD, water companies can use measurement data, which they already collect as part of normal operations, to gain a better understanding on how water is used and what the causes of changes in demand are. This can limit damages, save costs and increase insight. “Apart from determining leakage losses,” says De Kater, “you can use it to effectively monitor – and, ultimately, adjust – your operational management. We’re definitely going to continue with this, and will implement the method together with other filters to check our measurement data.”