Water and sewer project assessments costs vary due to the density of homes or geography of the area to be served. For instance, excavation through rock is much more expensive than excavation through soil. Water assessments on a single-family dwelling with approximately 100 feet of frontage have averaged between $6,000 and $23,000 over the last few projects that we have done. Sewer projects are generally more expensive due to more complex construction requirements. Assessments on both types of project vary greatly due to an area’s geography, the complexity of the project, the availability of grants, and the number of affected dwelling units.