Tex. Health & Safety Code § 372.0025

The governing body of a municipality or county by ordinance or order may allow the sale in the municipality or county of a urinal or toilet that does not comply with Section 372.002(b)(4) or (6), respectively, if the governing body finds that to flush a public sewer system located in the municipality or county in a manner consistent with public health, a greater quantity of water is required because of the configuration of the drainage systems of buildings located in the municipality or county or the public sewer system.