While all Wisconsin water utilities are regulated, sewer utility regulation is primarily a voluntary decision on the part of the municipality. Investor-owned sewer utilities would be regulated; however, none currently exist. Municipal sewerage systems - sanitary as well as storm water - do not fall within the definition of “public utility” under Wis. Stat. § 196.01(5) and therefore do not require PSC approval when setting rates and rules. There are over 600 sewer operations in Wisconsin. Of these systems, the PSC regulates two at present. These systems have elected to combine their water and sewer operations into a single public utility. For these two systems, the PSC regulates rates and rules, practices and procedures, plant additions, and service quality, among other areas.
Although the PSC does not regulate most sewer systems, it has limited authority over municipal sanitary sewer issues. Pursuant to Wis. Stat. § 66.0821(5)(a), any user of a sewer system may file a complaint with the Commission concerning the rates, rules, or practices of the municipality. Upon receiving a complaint, the PSC reviews the reasonableness of the municipality's rates, rules, and practices.