Tex. Water Code § 26.356

(a) For the purposes of developing or assisting in the development of a regulation, conducting a study, or enforcing this subchapter, an owner or operator of an underground or aboveground storage tank, on the request of the commission, shall:

(1) furnish information relating to the tank, including tank equipment and contents; and

(2) permit a designated agent or employee of the commission at all reasonable times to have access to and to copy all records relating to the tank.

(b) For the purposes of developing or assisting in the development of a regulation, conducting a study, or enforcing this subchapter, the commission, its designated agent, or employee may:

(1) enter at reasonable times an establishment or place in which an underground or aboveground storage tank is located;

(2) inspect and obtain samples of a regulated substance contained in the tank from any person; and

(3) conduct monitoring or testing of the tank, associated equipment, contents, or surrounding soils, air, surface water, or groundwater.

(c) The commission may order an owner or an operator of an underground or aboveground storage tank to conduct monitoring and testing if the commission finds that there is reasonable cause to believe that a release has occurred in the area in which the underground or aboveground storage tank is located.

(d) Each inspection made under this section must be begun and completed with reasonable promptness. Before a designated agent or employee of the commission enters private property to carry out a function authorized under this section, the agent or employee must give reasonable notice and exhibit proper identification to the manager or owner of the property or to another appropriate person, as provided by commission rule. The commission's designated agent or employee must observe the regulations of the establishment being inspected, including regulations regarding safety, internal security, and fire protection.