Houston, Texas
| Contaminant | Detected | EPA limit | EWG guideline | Status |
|---|---|---|---|---|
| Total Trihalomethanes (TTHMs) | 52.8 ppb | 80 ppb | 0.8 ppb | 66× EWG |
| Haloacetic Acids (HAA5) | 34.2 ppb | 60 ppb | 0.1 ppb | 342× EWG |
| Chloramine | 3.1 mg/L | 4 mg/L | — | — |
| Atrazine | 0.62 ppb | 3 ppb | 0.1 ppb | 6× EWG |
| Lead | 2.1 ppb | 15 ppb | 0.5 ppb | 4× EWG |
| PFAS (PFOA + PFOS) | 2.4 ppt | 4 ppt | 0.004 ppt | 600× EWG |
Context
Houston's warm climate and surface water sources drive high disinfection byproduct formation — THMs and HAAs are among the highest of major US cities, both exceeding EWG guidelines by 60-300x.
Atrazine, a widely used herbicide, is detected from agricultural runoff in the watersheds feeding Houston's water supply. Levels are below the EPA MCL but exceed the EWG guideline.
Houston experienced major water infrastructure stress during Winter Storm Uri (2021) and Hurricane Harvey (2017), with boil water notices affecting millions of residents.
The city has been transitioning from groundwater to surface water sources to address subsidence, which has changed the taste and contaminant profile of tap water in many neighborhoods.
Common questions
Is Houston tap water safe to drink?
Houston tap water meets EPA standards, but its warm climate drives some of the highest disinfection byproduct levels among major US cities. THMs exceed EWG guidelines by 66x and HAAs by 342x. A quality activated carbon filter is the most cost-effective improvement for Houston tap water.
Why does Houston water taste bad?
Houston's chloramine disinfection and high organic matter in surface water sources contribute to taste and odor issues. The transition from groundwater to surface water in many areas changed the taste profile. An activated carbon or catalytic carbon filter effectively removes chloramine taste and odor.
Does Houston water have forever chemicals?
PFAS has been detected in Houston water at approximately 2.4 ppt, below the EPA MCL of 4 ppt but far above the EWG guideline. Several sites in the Houston metro area, including petrochemical facilities and airports, are known PFAS contamination sources. RO and quality carbon filters reduce PFAS effectively.
Houston's water quality challenges are driven by its warm climate (which accelerates disinfection byproduct formation) and surface water sources in agricultural watersheds (which contribute atrazine). A good activated carbon filter handles the primary concerns — chloramine, THMs, HAAs, and atrazine — at a fraction of the cost of an RO system.
primarily surface water from Lake Houston, Lake Livingston, and the San Jacinto River, supplemented by groundwater from the Gulf Coast Aquifer
This data reflects system-wide testing. Your home's plumbing may add or reduce contaminants.
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