In a competitive market, property asset prices reflect the value of the services generated by a property for its owner, including productive and consumptive environmental services. The analysis of property values can therefore provide considerable insight into the benefits of programs that have environmental, recreation, health and amenity benefits for property owners. Three property valuation approaches can be used to estimate the benefits to households of environmental programs. These include statistical models of house prices, assessment of property price differentials by property valuation experts or by surveying property owners themselves to determine the value differentials they perceive. However, great care needs to be taken in using the expert or property owner valuation approaches. Estimated property price differentials “before” and “after” an environmental program may not reflect the full economic benefit to households if expectations of an environmental improvement have already been built into property values. This can greatly affect the outcome of a benefit cost analysis. An approach to estimating the economic benefits enjoyed by households about to be connected to a reticulated sewerage scheme, when expectations were already partly reflected in property prices, is detailed. The approach is illustrated using the case study of a proposal to provide reticulated sewerage to unsewered areas in Jamberoo, Stanwell Park, Stanwell Tops, Otford, Coalcliff, Brooklyn, Dangar Island, Mt Ku-ring-gai Industrial Area, Menangle, Menangle Park, Warragamba, Silverdale, Wallacia, Mulgoa, the Oaks, Oakdale and Belimbla Park.