The most obvious reason for using economic instruments, such as wastewater service fees or effluent charges, in wastewater management is the aim to raise revenue for financing service infrastructure or remedial actions for environmental damage. For recovery of costs of sanitation services, the polluter pays principle requires that not only the investment and operational costs of a treatment plant have to be covered, but also the costs that arise from the environmental damage linked with discharge of (treated) wastewater into surface waters.