Dear Nick,  I have been ...

Dear Nick, 

I have been involved in N.R.W. and water demand management since 30 years. As Igor and Kumar commented, you are engaging yourself in a very complex and lengthy process. It is impossible to reply in few lines and not even few books to your question. Water leak management requires deep involvement integrating miscellaneous technical as well as non technical components. But the fundamental principle is that you need to know your network. Before undertaking your leak investigations, you must understand the network configuration and the way it has been managed. You need to build a very comprehensive data base, starting with the reconciliation of drawings, technical data sheets, manufacturers brochures, SOP, incidents lists. You need a dedicated task force team and a reliable leader as well as the required authority to investigate the hidden "potential reasons". Once this is in place and depending on your targets and CAPEX budget, you can start field operations using smart meters (fixed or movables), as well as many other hardwares (DMA, PRV, .../...), using active leak detection (acoustic or other),.../...), GIS softwares and don't forget the local culture and habits. In many emerging countries, like the one I am presently (Indonesia), the non technical component can reach 60% in some places. It mainly comprises illegal connections or parallel illegal network, cheating (from client as well as staff), failing reporting procedures or administrative mistakes in data management, as few exemples. In any case, your leak investigation efforts will fail, if you do not have any clear understanding of your construction lay-out. If it is missing, you need to start investigating it. Don't start your leak management campaign if your network understanding is below 75%. Just to make sure for instance that valve in the drawing is really in the field and that the closed valve is actually closing... Of course you can progress at same speed with your network clarification and leak investigation, but give priority to clarify how is your network built. It's a fantastic task and your adrenaline will jump regularly as the leak grows . Good luck and do not hesitate to ask for advise