"During 2009-2010, RTI International developed and published a financial model which calculates the financially optimum level of Non-Revenue Water (NRW). The model computes a steady-state target for NRW reduction and control programs, based on site conditions and local costs. The model was presented at IWA Water Loss Specialist Conferences in Cape Town and Sao Paulo and other international meetings. It has been applied in over 30 countries using secondary data, and applied at a more detailed utility-level in Brazil, Jordan, Uganda, and Zambia. While the model has garnered considerable interest, it does not provide specific NRW program design guidance for utilities which are undertaking or interested to undertake the transition from a high level of losses to the lower, financially- optimal steady-state level of NRW.
This paper presents the conceptual framework for a new planning tool which guides utilities on developing an optimal NRW reduction program - one that reaches the optimal level of NRW at the lowest cost. The method, once fully developed at a given site, provides guidance on the optimal mix of actions to reduce commercial losses and the optimal mix of actions to reduce physical losses, based on site conditions and local costs. It also provides information on the schedule of cost inputs required (amount and timing) and the time line of NRW reduction that would be achieved over a multi-year period. Utilities can monitor actual results of their program and periodically update the NRW reduction program design based on empirical monitoring results and updated costs of inputs. The tool can also be used by governments, funders, and regulators to estimate costs and impacts of NRW reduction programs and conduct oversight. Utilities can also use to tool for defining terms and targets for NRW reduction contracts."