A Survey and Analysis of the Costs of Individual Onsite Septic Tank and Lagoon Treatment Systems

This paper evaluates the results of a survey of onsite wastewater treatment system installers, which was designed to elicit the costs of installing and operating onsite systems in Kansas. This information can be used by individuals to compare system costs and by government officials to design policies, which may include incentives to encourage the installation of new systems and replacement of failed systems. Septic tank-soil absorption systems and wastewater stabilization ponds or lagoons are the onsite wastewater systems most often used in the area surveyed for this study. The study includes summaries of the average installation costs of the components for each system and expected cost of maintenance. A life cycle cost analysis including installation and maintenance of each system for different household sizes was conducted. A sensitivity analysis also was performed to determine which factors have the greatest impact on the costs of each system. Results show that, although lagoon systems are somewhat less expensive initially, septic tank-soil absorption systems are more frequently installed in Kansas. A spreadsheet that can be used to calculate and compare the present value of the lifetime costs of owning and maintaining onsite wastewater treatment systems also is provided.