What is Cyclohexane and Why Does It Matter?

Cyclohexane is an industrial solvent derived from petroleum. It's a colorless liquid with a distinct gasoline-like odor, and it belongs to a class of chemicals called cyclic hydrocarbons. Most people encounter it indirectly — through industries that use it to manufacture nylon, rubber, paint, and adhesives. It enters drinking water primarily through industrial discharge, fuel spills, and leaking underground storage tanks. Stormwater runoff near refineries or manufacturing facilities can also carry cyclohexane into groundwater and surface water supplies.

The health picture with cyclohexane is still developing. Short-term exposure at high concentrations can cause dizziness, nausea, headaches, and irritation of the eyes and throat. Animal studies suggest that prolonged exposure may affect the nervous system and liver (EPA). At lower levels — like the average of 6.46 parts per billion (ppb) seen in detected systems — the risks are less clearly defined. That said, health researchers generally apply a precautionary approach to petroleum-based chemicals in drinking water, especially for children and pregnant women, whose bodies are more sensitive to chemical exposures.

Regulatory guidance on cyclohexane is limited. The EPA has not established a Maximum Contaminant Level (MCL) — the legal limit for a substance in public drinking water — specifically for cyclohexane. This means water systems are not legally required to reduce it, even when it shows up in testing. The Environmental Working Group (EWG) has similarly not published a specific health guideline for this compound. That regulatory gap is worth noting. Just because a contaminant lacks a legal limit doesn't mean it's harmless. It often means it hasn't been studied enough yet, or hasn't been detected widely enough to trigger regulatory action.

Geographically, the data tells a focused story. All 14 water systems where cyclohexane has been detected are located in Texas. That pattern isn't surprising. Texas has a dense concentration of oil refineries, petrochemical plants, and fuel storage facilities — particularly along the Gulf Coast and in the Permian Basin. These industries create more opportunities for petroleum-based chemicals to reach groundwater. Detected levels ranged up to a maximum of 51.0 ppb in at least one system, though the average across all 14 systems was 6.46 ppb. None of the detections exceeded a formal health guideline, but the presence of cyclohexane at all signals industrial influence on the local water supply.

If you live in Texas — especially near industrial corridors or petrochemical hubs — it's worth knowing what's in your water. The most effective way to remove cyclohexane from drinking water is through activated carbon filtration or reverse osmosis. Activated carbon works by adsorbing organic compounds like cyclohexane onto its porous surface as water passes through. Reverse osmosis goes a step further, pushing water through a semi-permeable membrane that blocks a wide range of contaminants, including petroleum-based chemicals. A quality reverse osmosis system can remove up to 99% of many organic contaminants from your tap water. Echo Water's systems combine both technologies, giving you layered protection against the kinds of industrial chemicals that don't always make headlines but still end up in your glass. If you're on a municipal system in Texas and want to know your specific risk, pulling your local Consumer Confidence Report (CCR) — the annual water quality report every public utility is required to publish — is a smart first step.

Regulatory Standards for Cyclohexane

Cities With the Highest Cyclohexane Levels

States Most Affected by Cyclohexane

Frequently Asked Questions

Related Contaminant Guides