Houston’s municipal water supply consistently meets or exceeds all federally mandated safety standards. Houston Public Works manages a large, complex system, ensuring the water is generally safe for consumption directly from the tap. However, water quality is dynamic, and its journey from the source to a homeowner’s glass involves multiple steps where quality can be affected. Understanding the source, treatment, and infrastructure risks provides a clearer picture of the city’s overall safety profile.
Source Water and Purification Methods
Houston’s water supply relies heavily on surface water sources, accounting for approximately 85% of the total volume distributed to residents. Primary sources include Lake Houston, Lake Livingston, and Lake Conroe. The remaining supply is drawn from groundwater aquifers, specifically the Chicot and Evangeline aquifers.
The raw water undergoes a multi-step treatment process. Initial treatment involves coagulation and sedimentation, where chemicals clump fine particles together so they settle out. This is followed by filtration, which removes remaining particulates. The final step is disinfection, typically achieved by adding chloramine to kill harmful bacteria and viruses and maintain disinfection power throughout the distribution network.
Safety Standards and Regulatory Compliance
The safety of Houston’s drinking water is overseen by the Environmental Protection Agency (EPA) and the Texas Commission on Environmental Quality (TCEQ). The city adheres to the Safe Drinking Water Act (SDWA), which sets Maximum Contaminant Levels (MCLs). Houston consistently reports that its water quality data meets these federal and state standards, documented in the annual Consumer Confidence Report (CCR).
Testing frequently detects trace amounts of contaminants, though levels remain within legal MCLs. Disinfection byproducts (TTHMs and HAA5) are monitored closely as they form when disinfectants react with organic matter. Naturally occurring elements like arsenic are also tracked, with reported levels typically below the EPA’s MCL. However, some organizations note that even compliant levels of certain substances, including unregulated contaminants like Chromium-6, may exceed more conservative health-based guidelines.
Infrastructure and Home Plumbing Risks
The quality of water at the consumer’s tap can differ from the quality leaving the treatment plant due to the distribution system and home plumbing. A significant concern involves aging infrastructure, particularly the service lines connecting main water pipes to individual properties. Homes built before 1986 are at the highest risk for having internal plumbing or service lines that contain lead or lead solder, which can leach into the water when stagnant.
The city is complying with the federal Lead and Copper Rule (LCR) revisions, which mandate creating a public inventory to plan for lead service line replacement. While the city reports its own service lines are not lead, the material composition of private service lines for many properties remains unknown. Residents in older homes should run the cold water tap for one to two minutes before drinking or cooking; this flushes out standing water that may have absorbed metals.
Improving Aesthetics and Choosing Filtration
While the water is safe from a regulatory standpoint, many residents notice aesthetic issues related to taste, odor, and hardness. The persistent chemical taste or smell is a common side effect of the chloramine used for continuous disinfection. Houston water is also considered very hard, with mineral content (primarily calcium and magnesium) often ranging from 140 to 300 parts per million (ppm).
This high mineral content causes scale buildup, leading many homeowners to seek softening solutions. To address the taste and odor from chloramine, a standard activated carbon filter is highly effective. For those seeking the highest water purity, a reverse osmosis (RO) system installed at the kitchen sink can remove up to 99% of dissolved solids.