Harris County, Texas: drinking water report. Harris County, home to Houston and 34 other incorporated cities, has a population exceeding 4.7 million.
Harris County, home to Houston and 34 other incorporated cities, has a population exceeding 4.7 million. The county's water supply is a mix of surface water from Lake Houston, Lake Conroe, and the Trinity River, plus groundwater from the Gulf Coast Aquifer. Decades of heavy groundwater pumping caused land subsidence of up to 10 feet in parts of the county, forcing a long transition toward surface water that is still ongoing. Multiple water authorities – the City of Houston, Harris County MUD districts, and independent utilities – serve different parts of this sprawling county.
Harris County sits along one of the largest petrochemical corridors in the world, and that proximity shows up in the water data. The EPA's UCMR5 program has flagged PFAS detections at sampling points across the county, with groundwater sources near the Houston Ship Channel and Ellington Field showing elevated readings. The Texas Commission on Environmental Quality monitors for PFAS but Texas has not yet adopted enforceable state MCLs, relying on federal thresholds.
Beyond PFAS, Harris County faces recurring challenges with disinfection byproducts. Treating warm, organic-rich surface water with chlorine produces trihalomethanes at levels that have periodically approached EPA limits. A 2024 TCEQ compliance report noted that 12 community water systems in Harris County had violations within the prior three years.
Your water quality in Harris County depends on which utility serves your home and whether that utility draws from surface water, groundwater, or a blend. MUD district water can differ sharply from City of Houston water just across the street.
Check your water to see monitoring data for your specific ZIP code. If you are in the Ship Channel area or near Ellington Field, a reverse osmosis system provides the broadest protection. Our water filter guide explains which filter types address PFAS versus disinfection byproducts. For historical context and trend data, grab your detailed report and visit our Texas page.