Government monitoring of the Helena Water System (CWS code MT0000241) in Lewis And Clark County, Montana, detected 1,4-dioxane in surface water supplying about 32,000 residents. Nine samples collected between mid-2013 and early 2014 showed one detection of this cyclic ether slightly above the reporting level of 0.07 micrograms per liter (µg/L), specifically 0.07335 µg/L or parts per billion (ppb). This finding is from the EPA’s Unregulated Contaminant Monitoring Rule (UCMR3), a survey focused on identifying emerging contaminants, not a compliance test with legal limits.
Why a Low-Level Detection Is Reported to Three Decimal Places and What Precision Means Here
The reporting of 1,4-dioxane at a value like 0.07335 µg/L indicates the sensitivity and precision of the federal testing method, which measures concentrations well below levels currently regulated by law. Such fine resolution helps establish a reliable record over time, but it does not imply the detection is a health violation or problem on its own. This precision distinguishes between trace presence and absence in the distribution system, enabling future trend tracking and risk assessment.
The Difference Between a UCMR3 Detection and a State Notification Level for Dioxane
While the EPA provides cancer risk reference concentrations—in this case, 0.35 µg/L for 1,4-dioxane—this is a health-based guideline, not a federal regulatory limit. Montana’s state notification level for 1,4-dioxane differs and generally triggers communication or action if concentrations rise above that guidance. The UCMR3 data for Helena shows 1,4-dioxane present but below all health-based indication thresholds and notification levels. This means public water records do not identify this constituent as a violation or unsafe exposure in the system.
How the Constituent Enters Groundwater or the Distribution System in This Region
In Lewis And Clark County, 1,4-dioxane primarily originates from industrial sources and chemical manufacturing practices historically involving solvent stabilizers. Because Helena’s water is surface-sourced, this cyclic ether can enter reservoirs and rivers from runoff or direct discharge. While not typically produced or released naturally, its persistence and mobility allow it to move through watersheds and treatment steps. No local plumbing materials contribute to 1,4-dioxane presence; it is solely an environmental contaminant in the source water context.
How the Treated Water Differs at the Tap Once the Documented Technology Is in Place
When a household’s existing equipment no longer meets treatment needs for 1,4-dioxane, the Autotrol 1,4-Dioxane Filter ships ready to configure as a direct purchase solution. This technology is designed to target and reduce levels of the cyclic ether from tap water effectively after municipal treatment. Once operational, the treated water shows substantially lowered 1,4-dioxane concentrations, improving consumer confidence without waiting for changes in the public system. The filtration approach specifically addresses the chemical’s characteristics, offering an outcome beyond general filtration or carbon-only units.
What a Certified Laboratory Test for This Constituent Reports and How to Read It
A certified lab analyzing household water for 1,4-dioxane will report results in micrograms per liter or parts per billion. The detection limit commonly aligns with or is below the EPA’s reporting level of 0.07 µg/L used in UCMR3. A test result that shows a number near or below this value means the cyclic ether is present at trace or very low concentration. Results above the lab’s reporting threshold, such as those slightly over 0.07 µg/L, confirm measurable amounts but do not alone prescribe health concerns or regulatory noncompliance. It remains essential to interpret these findings relative to health guidelines and source water data.
In summary, this briefing reviewed the government-recorded presence of 1,4-dioxane in the Helena Water System, emphasizing the precision and context of low-level detections, state notification versus federal guidelines, local water source contributions, household water quality improvements when the Autotrol technology is used, and the interpretation of certified laboratory water analyses. Together, these points guide a household deciding on treatment after prior equipment failure.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2014-04-16. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for Helena Water System (MT0000241), MT: 9 results across 1 listed contaminants, 1 detections above the reporting level; no federal MCL; EPA cancer risk reference concentration 0.35 ug/L