An industrial solvent classified as a likely carcinogen has been detected above the EPA's health advisory level in Cary and Apex tap water — and standard municipal treatment can't remove it.
Affects Jordan Lake water supply customers. Raleigh, Durham, and Chapel Hill are on separate sources.
Get a Free Water AssessmentContamination is tied to the Jordan Lake / Haw River supply. Cities on other sources are not impacted.
1,4-dioxane is one of the few contaminants that defeats conventional water treatment at every step.
| Treatment Method | Removal Rate | Effective? |
|---|---|---|
| Coagulation / flocculation | None | ✗ |
| Standard sand filtration | None | ✗ |
| Chlorine disinfection | None | ✗ |
| Granular activated carbon | 30–50% | ✗ |
| Reverse osmosis (point-of-use) | 80–95% | ✓ |
Source: EPA Unregulated Contaminant Monitoring Rule data and published treatment efficacy studies.
An under-sink reverse osmosis system removes 80–95% of 1,4-dioxane from your drinking and cooking water. It's the most effective residential option available.
Cary publishes annual Consumer Confidence Reports with 1,4-dioxane levels. Search "Cary NC CCR" or "TJCOG water report" to see your utility's most recent data.
The EPA added 1,4-dioxane to the Unregulated Contaminant Monitoring Rule. A federal MCL is estimated between 2027–2030, which will force municipal upgrades.
1,4-dioxane is a synthetic industrial solvent used in plastics manufacturing, cosmetics, and detergents. It enters the Haw River from industrial facilities in Burlington, Mebane, and Greensboro — cities upstream of Jordan Lake, which supplies Cary, Apex, and Morrisville. It's colorless, nearly odorless, and highly water-soluble, which makes it extremely difficult to remove with standard municipal treatment.
The EPA classifies 1,4-dioxane as a likely human carcinogen based on animal studies. Its health advisory threshold is 0.35 ppb. Cary tap water has tested at 0.5–1.2 ppb across multiple Consumer Confidence Reports — above the advisory level. That said, there's no enforceable federal maximum contaminant level yet; the EPA has estimated one may be finalized between 2027 and 2030.
1,4-dioxane resists coagulation, filtration, and chlorine disinfection — the three core steps in conventional municipal treatment. Granular activated carbon provides only partial removal (30–50%). It binds poorly to carbon because it's highly hydrophilic (water-loving), making it pass through most filtration media.
Reverse osmosis achieves 80–95% rejection of 1,4-dioxane at the point of use — significantly better than any other residential option. This is the most practical solution for homeowners on Jordan Lake water who want to reduce their exposure while municipal treatment technology catches up.
Raleigh draws from Falls Lake, not Jordan Lake. 1,4-dioxane contamination is specific to the Haw River watershed feeding Jordan Lake. Durham (Lake Michie) and Chapel Hill/Carrboro (OWASA) are also on separate supply systems and are not affected by this particular contaminant.
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