The impact of mechanical reliability on the financial return of a water-recycling plant

This paper presents results from the assessment of the financial viability of a water-recycling plant based on an estimate of 'net present value' including the impact of mechanical reliability. The 'net present value' of the former 0.6 Ml/d greywater recovery and re-use plant at the Millennium Dome, London was calculated over an expected lifetime of 20 years and a capital cost of 2.2 million Euro. A detailed analysis of the mechanical faults and shutdowns at the plant showed an improvement in reliability from 73.8% to 91.2%, attainable by investing in a dedicated critical-spares facility. Defining the break-even price of water as the price for which 'net present value' is zero, the model showed the break-even price to decrease from 1.61/m(3) Euro to 1.40/m(3) Euro by increasing reliability over the above range of values. The paper discusses the implications of this research for water-recycling applications in general.