(a) The district consists of the territory included in the incorporated city of Brookshire in Waller County, Texas, on April 1, 1951. The district's territory may have been modified under:
(1) Chapter 3A, Title 128, Revised Statutes, before August 30, 1971;
(2) Subchapter O, Chapter 51, Water Code;
(3) Subchapter J, Chapter 49, Water Code; or
(4) other law.
(b) A defect in the definition of the boundaries of the city of Brookshire or in a past proceeding for the annexation or exclusion of territory to or from the city does not affect the validity of the district or any of its powers and duties.