Tex. Water Code § 55.369: FIXED CHARGES FOR MAINTENANCE EXPENSES.

If maintenance charges are based on the quantity of water used, a fixed charge may be made on all land or water connections entitled to receive and use water. An additional charge may be made, or a graduated scale adopted, for the use of more water than that covered by the minimum charge. The board may install proper measuring devices.

Acts 1971, 62nd Leg., p. 458, ch. 58, Sec. 1, eff. Aug. 30, 1971.