John I am not entirely sure ...
Published by Richard Burns, Managing Director at EcoKIS Ltd
John
I am not entirely sure about your definition of LWLI. IWA uses Infrastructure Leakage Index (IFI) and in France the Linear Leakage Index (LLI) is in use. Eddy Renaud's paper at https://hal.archives-ouvertes.fr/hal-00593479/document provides a comprehensive and detailed presentation of these and other indices including their formulae and worked examples.
I would also support earlier references to the IWA Manual of Best Practice; Performance Indicators for Water Supply Services (3rd edition) http://www.iwapublishing.com/books/9781843390510/performance-indicators-water-supply-services-second-edition. In addition I recommend "Losses in Water Distribution Systems - A Practitioners Guide to Assessment, Monitoring and Control" by Malcolm Farley and Stuart Trow (http://www.iwapublishing.com/books/9781900222112/losses-water-distribution-networks) and all Allan Lambert's work.
As a general introduction on water losses "Sustainable Water" published by ICE is a good reference (http://www.icebookshop.com/bookshop_main.asp?ISBN=9780727757739).
Good luck with your project.