For the purpose of this act, the following words and phrases shall have the meaning ascribed to them in this section:
(a) "Sewer" or "sewer system" shall mean sanitary and storm sewers, pumping stations, sewage treatment plants, main sewers, intercepting sewers, outfall sewers, surface drains and works for the collection, transportation, pumping, treating, and disposing of water carried wastes or storm or surface waters, and all appurtenances necessary in the maintenance and operation of the same.
(b) "Municipality" shall mean any city, county, township, township sewer district, or other political subdivision of the state authorized to levy taxes or empowered to cause taxes to be levied.