City of Houston -- Public Works and Engineering -- Resource Management Division -- Utility Customer Service -- FAQ's -- Page 11

Water rates are set to cover the cost of acquisition, treatment and delivery of water to your tap and are adjusted annually based on the increase in costs in the region. In this way, large rate increases are avoided, and the city is able to ensure that Superior Quality water is provided to you and approximately 2.7 million other customers. Rates must also cover costs of scheduled replacement of aging water lines, the building of new treatment facilities as needed and the cost of ensuring that our water supply is secure. Houston is proud of having maintained a five-year record of providing safe and reliable drinking water of Superior Quality as set by the Texas Commission on Environmental Quality.