Reducing Non-revenue Water

Many water companies are looking to invest a lot of money in renovating the pipe network in order to reduce non-revenue, but is this really the best way of doing things? When leaking pipes are exchanged and nothing is done to the pump control, then the pressure in the rest of the network simply increases. Looking at the below graph, it is quite clear, that as pressure increases, so does the water losses. 

I tried to make a calculation of the impact with a 4 mm hole in the pipe with a 4 bar system pressure:

Exchanging only some of the pipework, could therefor in a worst case scenario cause higher water losses, than before the exchange.

It is very important, that the pressure is controlled in the rest of the system, when pipework is exchanged, to avoid increasing the pressure in the old pipes. If pressure is not controlled, then pressure increase in the remaining old pipes may not only increase waterlosses, but also cause increased risk of pipe damages and maintenance cost for damages to check valves and other equipment.

Installing variable speed drives in the system before exchanging the pipes will provide an immidiate saving in non-revenue water, even before exchanging any pipes and will also prevent an increase in non-revenue water, as renovations of the pipework progresses.