The West Harris County Regional Water Authority represents an area located between U.S.290 and the Harris-Waller county line that is larger than the City of Pittsburgh.

The North Harris County Regional Water Authority is responsible for an area located generally between U.S.290 and U.S. 59; and the Central Harris County Regional Water Authority is made up of 11 MUDs in the area near SH 249 and Beltway 8. The North Fort Bend Water Authority includes the City of Fulshear and MUDs in Fort Bend County located south of I-10, east of the western area of Fulshear, north of the cities of Sugar Land, Richmond and Rosenberg, and west of the Fort Bend-Harris county line.