(a) A person who operates a public water supply on a contract or volunteer basis must hold a registration issued by the commission under Chapter 37, Water Code.
(b) A person who performs process control duties in production or distribution of drinking water for a public water system must hold a license issued by the commission under Chapter 37, Water Code, unless:
(1) the duties are provided to a transient, noncommunity water system; and
(2) the water system uses groundwater that is not under the influence of surface water.

(c) A person who repairs or tests the installation or operation of backflow prevention assemblies must hold a license issued by the commission under Chapter 37, Water Code.
(d) A person who inspects homes and businesses to identify potential or actual cross-connections or other contaminant hazards in public water systems must hold a license issued by the commission under Chapter 37, Water Code, unless the person is licensed by the Texas State Board of Plumbing Examiners as a plumbing inspector or water supply protection specialist.
(e) Unless the person is licensed by the Texas State Board of Plumbing Examiners, a person must hold a license issued by the commission under Chapter 37, Water Code, if, under a contract, the person:
(1) installs, exchanges, connects, maintains, or services potable water treatment equipment and appliances in public or private water systems; or
(2) analyzes water to determine how to treat influent or effluent water, alter or purify water, or add or remove a mineral, chemical, or bacterial content or substance as part of the complete installation, exchange, connection, maintenance, or service of potable water treatment equipment and appliances.