1,4‐Dioxane is an “emerging contaminant” that is found in drinking water supplies throughout the United States. It is a human carcinogen, and it may also cause kidney and liver damage with long‐term exposure. The physical and chemical properties and behavior of 1,4‐Dioxane create challenges for its treatment. It is highly soluble in water, and is not readily biodegradable. The EPA has determined that the drinking water concentration representing a 1 x 10‐6 cancer risk level for 1,4‐Dioxane is 0.35 µg/L.

Because 1,4‐Dioxane is used to stabilize chlorinated solvents, it is often associated with solvent contaminant plumes in groundwater. 1,4‐Dioxane is also found in numerous products. It is used in the manufacture of paint strippers, greases, waxes, dyes, varnishes, and consumer products (deodorant, shampoos, and cosmetics), and is present in antifreeze and aircraft deicing fluids. Due to its high solubility, it tends to be found at the leading edge of plumes in advance of other contaminants.


No federal maximum contaminant level (MCL) has yet been established for 1,4‐Dioxane in drinking water, although states have health‐based drinking water guidance values. 1,4‐Dioxane was included on the third drinking water contaminant candidate list (CCL), which is a list of unregulated contaminants that are known to, or anticipated to, occur in public water systems, and may require regulation under the Safe Drinking Water Act. Out of all the Public Water Supplies that were tested under the Unregulated Contaminant Monitoring Rule 3 (UCMR‐3), Massachusetts was a state with one of the most detections of 1,4‐Dioxane (76%). Several state governments have set their own varying advisory levels for 1,4‐Dioxane, and the table below provides a sampling of these states.

Regulatory Guidelines for 1,4‐Dioxane in Drinking Water for Selected States

StateGuidelineConcentration (µg/L)
CaliforniaNotification Level1.0
ColoradoDrinking Water Standard3.2
ConnecticutAction Level3.0
FloridaHealth Advisory Level0.35
MaineMaximum Exposure Guideline4.0
New HampshireProposed Remediation Value3.0
New YorkDrinking Water Standard50

Treatment and Path Forward

1,4‐Dioxane is difficult to treat because it is very soluble in water, and it has low volatility so that aeration cannot effectively remove it. It has been shown that advanced oxidation process (AOP) treatment can be very effective for treating 1,4‐Dioxane.

Having been impacted by 1,4-Dioxane in one of its higher production wells, a Community Water Supply in Massachusetts has proactively begun piloting AOP utilizing ultraviolet light and hydrogen peroxide for its removal. Wright-Pierce is implementing the pilot program, and results are indicating an ability to treat it to non-detectable levels.

If you have 1,4-Dioxane in your water supply, Wright‐Pierce can offer guidance and strategies on treatment approaches like the case described above. For more information, please contact us today.