Tex. Water Code § 13.143

(a) A utility may implement as part of its billing process a program under which the utility collects from its customers a voluntary contribution, including a voluntary membership or subscription fee, on behalf of a local library, a volunteer fire department, or an emergency medical service.

(b) A utility that collects contributions under this section shall provide each customer at the time that the customer first becomes a customer, and at least annually thereafter, a written statement:

(1) describing the procedure by which the customer may make a contribution with the customer's bill payment;

(2) designating the local library, volunteer fire department, or emergency medical service to which the utility will deliver the contribution;

(3) informing the customer that a contribution is voluntary; and

(4) describing the deductibility status of the contribution under federal income tax law.

(c) A billing by the utility that includes a voluntary contribution under this section must clearly state that the contribution is voluntary and that it may be deducted from the billed amount.

(d) The utility shall promptly deliver contributions that it collects under this section to the designated local library, volunteer fire department, or emergency medical service, except that the utility may keep from the contributions an amount equal to the lesser of:

(1) the utility's expenses in administering the contribution program; or

(2) five percent of the amount collected as contributions.

(e) Amounts collected under this section are not rates and are not subject to regulatory assessments, late payment penalties, or other utility-related fees and are not required to be shown in tariffs filed with the regulatory authority.