The public water system record for the City of Houston serving Harris County, TX, shows that 1,4-dioxane—the cyclic ether used as a solvent stabilizer—was detected in surface water sources. Among 103 samples taken between July 2013 and May 2014, 8 measurements surpassed the reporting level of 0.07 micrograms per liter (µg/L), with the highest detected concentration recorded at 0.091 µg/L. This data reflects the system's water quality overall, not the exact condition of any single household's water supply.
If You Notice 1,4-Dioxane Reported to Three Decimal Places—What Does the Precision Mean?
When government sampling reports 1,4-dioxane to the thousandth of a microgram per liter (parts per billion), this level of precision indicates the sensitivity of the measuring instruments rather than a precise health risk designation. The presence of detections in this low range demonstrates the capability to identify very small concentrations of the solvent stabilizer. However, these figures alone do not determine whether your water exceeds any health standard because no federal maximum contaminant level (MCL) exists for 1,4-dioxane.
If You Wonder Why 1,4-Dioxane Can Appear Ahead of the Original Solvent Plume
1,4-dioxane is known for its unusually high mobility in groundwater compared to other co-occurring solvents. Because it dissolves readily and resists natural breakdown, it often moves ahead of the solvent plume it was originally used to stabilize. This characteristic means that, even if other solvents are undetected or present at lower levels, the cyclic ether might still be measurable downstream or downgradient of an industrial source or water intake. For household water users, this explains the potential for finding low concentrations in treated surface water supplies.
If Your Water Source or Sample Depth Differs, How Does This Impact Expected 1,4-Dioxane Levels?
The City of Houston's water system draws from surface water sources, which generally differ from private wells or deep aquifer samples in chemistry and contaminant profiles. Households relying on groundwater or private wells should arrange for independent testing to understand their specific water quality. For surface-supplied homes like those in Harris County connected to the city system, the published data reflects overall system conditions rather than localized variations at individual taps.
If You Use the Record’s Median and Range for Guidance: What It Shows at Home
The median concentration of detected 1,4-dioxane in the Houston system was approximately 0.0755 µg/L, with the highest detection near 0.091 µg/L. This range falls well below the EPA cancer risk reference concentration of 0.35 µg/L. While the term "detected" means the instrument measured some amount, it does not imply a violation or health hazard. These numbers provide a context for what to expect from municipal surface water in the area but cannot replace personal water testing when precision is required for your household.
If You Compare Detected Levels to Federal Standards, What Does This Mean and What It Doesn’t?
Currently, no federal MCL exists for 1,4-dioxane; therefore, detected levels in municipal water from Houston’s system are not violations or indications of unsafe water. The EPA’s cancer risk reference concentration offers a benchmark for assessing potential risk, but detections below this level do not establish a health hazard nor confirm complete safety. Understanding these distinctions helps prevent overinterpretation of government data, especially when household water treatment equipment has failed and concerns arise.
These government-supplied records describe system-wide monitoring results that cover a large population in Harris County and do not directly translate into your home’s water quality. To know your own water’s 1,4-dioxane level, specific testing of your supply is necessary. For households facing existing equipment failure and seeking an effective response, the Autotrol 1,4-Dioxane Filter ships ready to configure for direct purchase and is designed specifically to address the presence of this cyclic ether in residential water supplies.
All information is based on the EPA SDWIS public water system record for the City of Houston (TX1010013), covering monitoring from 2013 to 2015. For further details, consult the official EPA UCMR data repository.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2014-05-27. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for City of Houston (TX1010013), TX: 103 results across 1 listed contaminants, 8 detections above the reporting level; no federal MCL; EPA cancer risk reference concentration 0.35 ug/L
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