Tex. Water Code § 16.403

(a) The board and the commission, in consultation with the Water Conservation Advisory Council, shall develop a uniform, consistent methodology and guidance for calculating water use and conservation to be used by a municipality or water utility in developing water conservation plans and preparing reports required under this code. At a minimum, the methodology and guidance must include:

(1) a method of calculating total water use by a municipality or water utility, including water billed and nonrevenue water used, and a method of calculating water use for each sector of water users served by a municipality or water utility;

(2) a method of calculating total water use by a municipality or water utility in gallons per capita per day;

(3) a method of classifying water users within sectors;

(4) a method of calculating water use in the residential sector that includes both single-family and multifamily residences, in gallons per capita per day;

(5) a method of calculating water use in the industrial, agricultural, commercial, and institutional sectors that is not dependent on a municipality's population or the number of customers served by a water utility; and

(6) guidelines on the use of service populations by a municipality or water utility in developing a per-capita-based method of calculation, including guidance on the use of permanent and temporary populations in making calculations.

(b) The board or the commission, as appropriate, shall use the methodology and guidance developed under Subsection (a) in evaluating a water conservation plan, program of water conservation, survey, or other report relating to water conservation submitted to the board or the commission under:

(1) Section 11.1271;

(2) Section 13.146;

(3) Section 16.012(m);

(4) Section 16.402; or

(5) Section 16.4021.

(c) The board, in consultation with the commission and the Water Conservation Advisory Council, shall develop a data collection and reporting program for municipalities and water utilities with more than 3,300 connections.

(d) The board shall make publicly available the most recent data relating to:

(1) statewide water usage in the residential, industrial, agricultural, commercial, and institutional sectors; and

(2) the data collection and reporting program developed under Subsection (c).

(e) Data included in a water conservation plan or report required under this code and submitted to the board or commission must be interpreted in the context of variations in local water use. The data may not be the only factor considered by the commission in determining the highest practicable level of water conservation and efficiency achievable in the jurisdiction of a municipality or water utility for purposes of Section 11.085(l).