Benefit-cost analysis has been used by the authors for 25 years to evaluate and prioritize potential conservation measures. With the advent of recent and better data on how customers use water, such as provided by the AWWARF Residential and Commercial/Institutional End Use Studies, the water savings estimates can now be made at the end use level. This increased level of complexity is justified by more reliable results. The task of computing estimated water savings and doing benefit-cost analysis is more accurate with the use of an end use model. This paper describes experiences using such a model for more than 100 communities over the last five years. The model, called the Least Cost Planning Demand Management Decision Support System, or DSS Model, has been used for projects large and small, sometimes involving separate DSS Models for up to 30 communities in a regional area. The number of measures for each study evaluated ranged from 15 to 35. In each case some measures were cost-effective while others were not. Projected water savings for recommended programs ranged from a few percent, on top of programs already in place, such as plumbing and appliance codes, to upwards of ten percent. Total savings including both can be in the range of 10-20 percent after 20 to 30 years of implementation. The amount of effort involved in this more detailed approach is significant. However, the benefits of using this approach outweigh the additional effort involved. The calibration process provides additional insight into how customers use water and verifies that the demographic and water use data are consistent and appropriate for the service area. The ability to evaluate a large number of measures and alternative programs relatively quickly enhances the water planner's ability to be creative on program design. Includes tables, figures.