Tex. Local Government Code § 212.003

(a) The governing body of a municipality by ordinance may extend to the extraterritorial jurisdiction of the municipality the application of municipal ordinances adopted under Section 212.002 and other municipal ordinances relating to access to public roads or the pumping, extraction, and use of groundwater by persons other than retail public utilities, as defined by Section 13.002, Water Code, for the purpose of preventing the use or contact with groundwater that presents an actual or potential threat to human health. However, unless otherwise authorized by state law, in its extraterritorial jurisdiction a municipality shall not regulate:

(1) the use of any building or property for business, industrial, residential, or other purposes;

(2) the bulk, height, or number of buildings constructed on a particular tract of land;

(3) the size of a building that can be constructed on a particular tract of land, including without limitation any restriction on the ratio of building floor space to the land square footage;

(4) the number of residential units that can be built per acre of land; or

(5) the size, type, or method of construction of a water or wastewater facility that can be constructed to serve a developed tract of land if:

(A) the facility meets the minimum standards established for water or wastewater facilities by state and federal regulatory entities; and

(B) the developed tract of land is:

(i) located in a county with a population of 2.8 million or more; and

(ii) served by:

(a) on-site septic systems constructed before September 1, 2001, that fail to provide adequate services; or

(b) on-site water wells constructed before September 1, 2001, that fail to provide an adequate supply of safe drinking water.

(b) A fine or criminal penalty prescribed by the ordinance does not apply to a violation in the extraterritorial jurisdiction.

(c) The municipality is entitled to appropriate injunctive relief in district court to enjoin a violation of municipal ordinances or codes applicable in the extraterritorial jurisdiction.