Understanding 1,4-Dioxane in Iredell Household Water and What It Means

C-Series 1,4-Dioxane Filter

Request a Quote

View full details

Reverse Osmosis Rejection Rates and Their Limitations

Percentage removal claims do not guarantee zero 1,4-dioxane

While reverse osmosis (RO) technology is commonly cited with percentage figures for its ability to reduce 1,4-dioxane, these percentages reflect laboratory conditions and do not guarantee the same performance in home applications. The cyclic ether’s small molecular size and solubility can limit RO effectiveness depending on system design and maintenance. Homeowners should understand that RO’s percentage figures are a laboratory metric, not a full assurance of the constituent’s absence.

Movement of 1,4-Dioxane Beyond Its Stabilized Solvent Source

Dioxane migrates ahead of the solvent plume it stabilizes

1,4-dioxane, also called the solvent stabiliser, is known to migrate faster and farther in groundwater and surface water than the solvents it accompanies. This means that its detection downgradient from a contamination site can occur even when solvent concentrations are low or absent. For households supplied by surface water in Statesville, this behavior means 1,4-dioxane may be found independently of other solvent indicators in the same water source.

Influence of Sample Depth, Well Depth, and Source Type

Surface water sources display different 1,4-dioxane levels than deep wells

The Iredell Water Corporation uses surface water to supply Statesville. Surface water bodies are more directly exposed to environmental inputs and may show seasonal and localized fluctuations in cyclic ether levels. In contrast, deep groundwater wells typically show more stable but potentially different contaminant profiles. Therefore, the results of 1,4-dioxane tests can vary significantly based on whether the water source is surface or groundwater and the depth at which samples are taken.

Seasonal and Multi-Year Variation in 1,4-Dioxane Measurements

Records from 2013 to 2015 show sporadic detections at low levels

Government sampling under the EPA’s Unregulated Contaminant Monitoring Rule (UCMR3) for the Iredell Water Corporation between April 2013 and December 2015 found 1,4-dioxane in 11 out of 64 samples. Detected levels ranged from just above the reporting limit of 0.07 micrograms per liter (µg/L) — equivalent to 0.07 parts per billion (ppb) — up to 0.21 µg/L, with a median detection of 0.085 µg/L. These values are below the EPA’s cancer risk reference concentration of 0.35 µg/L, indicating that the EPA does not have a maximum contaminant level (MCL) set for this cyclic ether in this system. The detections illustrate seasonal or multi-year fluctuations rather than consistent elevated presence.

Steps to Rule Out or Confirm Household 1,4-Dioxane Presence

Start with reviewing local water system reports before testing household water

• Check the public water system record for your area, such as Iredell Water Corporation’s results covering Statesville.
• Understand that detections reported by the system are not health violations but measurements of presence at low concentrations.
• If concerned about your household’s water quality, order a laboratory test specifically for 1,4-dioxane to establish your home’s water conditions, since individual pipes and treatment devices can affect water quality.
• Remember that aesthetic or secondary standards relevant to taste or staining do not apply to 1,4-dioxane.

The single most conclusive step is to obtain a certified laboratory analysis of your household water for 1,4-dioxane. A test result near or below the highest median detections reported by the local system (approximately 0.085 µg/L or 0.085 ppb) suggests your water quality reflects typical regional levels as measured in surface water supplies.

For homes requiring a point-of-entry solution to address the cyclic ether, the C-Series 1,4-Dioxane Filter ships ready to configure and is documented to reduce this challenging compound from household water. This equipment may be considered once test results confirm the need for targeted water treatment.

Where this information comes from

Source: EPA SDWIS public water system record. Sampled 2015-12-09. These figures describe the public water system's record, not the plumbing inside any individual building.

On record: EPA UCMR3 monitoring (2013-2015) for Iredell Water Corporation (NC0149025), NC: 64 results across 1 listed contaminants, 11 detections above the reporting level; no federal MCL; EPA cancer risk reference concentration 0.35 ug/L