This subsection shall not affect the landlord's duty under Subchapter B to repair or remedy, at the landlord's expense, wastewater stoppages or backups caused by deterioration, breakage, roots, ground conditions, faulty construction, or malfunctioning equipment. A landlord and tenant may agree to the provisions of this subsection only if the agreement meets the requirements of Subdivision (4) of Subsection (e) of this section.
Tex. Prop. Code § 92.006