In all municipalities where a system of public waterworks is maintained and operated, or created, the municipal governing body shall have power to cause a general sanitary, storm or combination sewer system to be established, which shall be composed of two classes of sewers: public and district sewers. The governing body may also cause a water distribution system and water supply facilities to be established composed of public and district water distribution lines. Such systems may be created separately or in conjunction with each other.
Okla. Stat. tit. 11, § 37-202