Houston Water Hardness & Quality Report (2026)

Houston Public Works operates the municipal water system serving approximately 2.4 million people across Harris County and surrounding areas in southeast Texas. Primary sources include surface water from the San Jacinto River (Lake Conroe and Lake Houston) and the Trinity River (Lake Livingston), supplemented by 104 wells tapping the Evangeline and Chicot aquifers. Water is treated at three major surface water treatment plants and around 40 groundwater plants, with 16 additional facilities for peripheral systems. The main system is designated TX1010013 by the EPA.

The supply originates in the San Jacinto and Trinity River watersheds within the Gulf Coastal Plain physiographic province. These drainages traverse Tertiary and Quaternary sediments, including Miocene Oakville sands and Pliocene Lagarto clays, underlain by limestone-bearing formations. Groundwater from the Chicot aquifer (Pleistocene sands and gravels) and the Evangeline aquifer (Miocene sands) interacts with calcareous shell fragments and limestone lenses, yielding a hard supply with elevated dissolved minerals. Surface water acquires similar chemistry from limestone-rich soils, producing consistently mineralized character across blended sources.

Hard water promotes scale buildup in pipes, heaters, and fixtures, and shortens the lifespan of water heaters, dishwashers, washing machines, and coffee makers while increasing energy costs. Regular vinegar descaling, scale-inhibiting filters, and annual system flushing help manage deposits. A whole-home water softener is widely recommended to improve soap lathering, prevent spots on glassware, and protect plumbing longevity. Water maintains neutral to slightly alkaline pH; 90th percentile lead levels are low at 4 ppb. Notable unregulated concerns include TTHM at 45 ppb, arsenic averaging 2.3 ppb (max 8 ppb), and chromium-6 at 747 ppt, all below MCLs. No specific PFAS data noted in available reports.