Tex. Water Code § 13.247

(a) If an area is within the boundaries of a municipality, all retail public utilities certified or entitled to certification under this chapter to provide service or operate facilities in that area may continue and extend service in its area of public convenience and necessity within the area pursuant to the rights granted by its certificate and this chapter, unless the municipality exercises its power of eminent domain to acquire the property of the retail public utility under Subsection (d). Except as provided by Section 13.2475 or 13.255, a municipally owned or operated utility may not provide retail water and sewer utility service within the area certificated to another retail public utility without first having obtained from the utility commission a certificate of public convenience and necessity that includes the areas to be served.

(b) Notwithstanding any other provision of law, a retail public utility may continue and extend service within its area of public convenience and necessity and utilize the roads, streets, highways, alleys, and public property to furnish retail utility service, subject to the authority of the governing body of a municipality to require any retail public utility, at its own expense, to relocate its facilities to permit the widening or straightening of streets, by giving to the retail public utility 30 days' notice and specifying the new location for the facilities along the right-of-way of the street or streets.

(c) This section may not be construed as limiting the power of municipalities to incorporate or extend their boundaries by annexation, or as prohibiting any municipality from levying taxes and other special charges for the use of the streets as are authorized by Section 182.025, Tax Code.

(d) In addition to any other rights provided by law, a municipality with a population of more than 500,000 may exercise the power of eminent domain in the manner provided by Chapter 21, Property Code, to acquire a substandard water or sewer system if all the facilities of the system are located entirely within the municipality's boundaries. The municipality shall pay just and adequate compensation for the property. In this subsection, "substandard water or sewer system" means a system that is not in compliance with the municipality's standards for water and wastewater service.