Determining maintenance requirements of a water distribution network using whole life costing

A whole life costing (WLC) methodology has been developed for determining long term maintenance expenditure requirements for water distribution networks. The methodology utilises an accounting scheme that ties the costs incurred by the operator and other stakeholders to the attributes or performance that drive the costs. It has specifically been derived with the requirements placed by the regulatory regime on the water companies that operate in England and Wales in mind. Expenditure constraints are implied by the regulator through price caps that companies can charge their customers. Appropriate levels of expenditures included as part of the price cap determinations are required by the regulator to be economically robust and tied to the service received by the customers. Therefore, maintenance decisions must reflect more immediate concerns of meeting performance requirements, but must ensure that such levels are sustainable in the long term. The WLC methodology achieves this through an integrated platform that links costs identified within a structured accounting scheme with their performance based drivers commonly modelled based on historical data. Thus, a robust and fully auditable methodology is provided that can address the requirements of all stakeholders. This methodology is the basis for software (WiLCO) that provides decision support in determining appropriate pipe rehabilitation and operational strategy and thus expenditure levels over extended time horizons.