1,1-Dichloroethane in Drinking Water: Complete Guide (2026)

What is 1,1-Dichloroethane and Why Does It Matter?

# 1,1-Dichloroethane: What You Need to Know

1,1-Dichloroethane is a colorless liquid chemical that smells faintly sweet. It's used primarily in the production of refrigerants and as a solvent in various industrial processes. The chemical enters drinking water supplies mainly through leaks at manufacturing facilities, improper disposal of industrial waste, and contamination from dry cleaning operations. Once released into groundwater, 1,1-dichloroethane persists for years because it breaks down very slowly in the environment.

The good news: most people exposed to this contaminant face minimal risk at current levels. The EPA sets the legal drinking water limit at 5 parts per billion (ppb). The Environmental Working Group (EWG), which applies stricter health-based standards, recommends a guideline of 0.7 ppb. At low exposure levels, the chemical shows minimal health effects in humans. However, animal studies suggest that chronic exposure at higher concentrations may increase the risk of liver and kidney damage, along with potential nervous system effects. The data shows that no water systems in the U.S. currently exceed the EPA's legal limit, though some systems do contain detectable amounts.

Currently, 437 water systems across the United States have detected 1,1-dichloroethane in their supplies. The average concentration is 0.066 ppb—well below EPA standards. However, one system in California recorded a maximum of 1.88 ppb, which exceeds the EWG guideline but remains below the EPA limit. This distinction matters: the EPA limit is designed to prevent serious health problems, while the EWG guideline aims to minimize even small risks over a lifetime of exposure. If you live in an area where your water utility reports detecting this chemical, you're not facing an immediate health crisis, but you may want to take steps to reduce your exposure further.

Geographic patterns reveal which regions face the highest detection rates. California leads with 84 systems detecting the chemical, followed by New Jersey (53 systems), New York (49), Alabama (29), and Pennsylvania (23). These states share common characteristics: they have significant industrial histories, particularly in manufacturing and chemical production. California's detections concentrate in areas with heavy semiconductor and electronics manufacturing. New Jersey's cases cluster near former dry cleaning operations and industrial zones. The Northeast's pattern reflects decades of industrial activity and older groundwater contamination from past disposal practices. Southern states like Alabama show contamination linked to chemical manufacturing facilities. If you live in these regions, it's worth checking your water utility's annual water quality report to see if 1,1-dichloroethane appears on your local list.

Removing 1,1-dichloroethane requires filtration methods that target volatile organic compounds (VOCs). Activated carbon filters effectively trap this chemical—both whole-home systems and pitcher-style filters work, though whole-home systems provide more comprehensive protection. Reverse osmosis systems remove up to 99% of 1,1-dichloroethane from your drinking water. For the most reliable protection, combine activated carbon with reverse osmosis, which addresses this contaminant plus hundreds of others. If your water utility's report shows 1,1-dichloroethane detection, request the specific concentration. If it's below 0.7 ppb, a quality activated carbon filter addresses the concern affordably. If levels approach or exceed the EWG guideline, a reverse osmosis system provides stronger assurance. Start by requesting your local water quality report from your utility—it's free and shows exactly which contaminants are present in your water.

Regulatory Standards for 1,1-Dichloroethane

Cities With the Highest 1,1-Dichloroethane Levels

States Most Affected by 1,1-Dichloroethane

Frequently Asked Questions

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