Tex. Gov't Code § 3000.005

If any provision of a rule, charter provision, ordinance, order, building code, or other regulation described by Section 3000.002(a) is held invalid under this chapter, the invalidity does not affect other provisions or applications of the rule, charter provision, ordinance, order, building code, or other regulation that can be given effect without the invalid provision or application, and to this end the provisions of the rule, charter provision, ordinance, order, building code, or other regulation are severable.