Tetrachloroethylene (perchloroethylene) in Drinking Water: Complete Guide (2026)

What is Tetrachloroethylene (perchloroethylene) and Why Does It Matter?

# Tetrachloroethylene (Perchloroethylene): What You Need to Know

Tetrachloroethylene, commonly called PCE or "perc," is a colorless, odorless chemical that's been a workhorse in American industry for decades. Dry cleaners use it to clean clothes. Metal manufacturers use it to degrease parts. Textile mills use it to process fabrics. When these businesses dispose of waste improperly — or when underground storage tanks leak — PCE seeps into groundwater and eventually into drinking water supplies. Our data shows 485 water systems across the United States exceed the EWG health guideline for PCE, with contamination levels averaging 0.601 parts per billion (ppb). In some cases, contamination reaches as high as 8.64 ppb, nearly 15 times higher than what health experts recommend.

The health effects of PCE exposure depend on how much you drink and for how long. Short-term exposure to high levels can cause dizziness, headaches, and liver damage. Long-term exposure at lower levels is the real concern for most families. The International Agency for Research on Cancer (IARC) classifies PCE as a probable human carcinogen. Studies have linked chronic PCE exposure to increased kidney cancer risk and bladder cancer risk. Pregnant women face additional concerns — research from the National Institutes of Health suggests PCE exposure during pregnancy may affect fetal development. Children are particularly vulnerable because their bodies are still developing and they drink more water per pound of body weight than adults.

Here's where regulation gets complicated. The EPA's legal limit for PCE in drinking water is 5 ppb. That sounds protective, but the Environmental Working Group (EWG) has set a much stricter health guideline of just 0.17 ppb based on cancer risk data. This gap matters: 485 water systems exceed the EWG guideline, but only a fraction exceed the EPA's legal limit. That doesn't mean the EPA is wrong — it reflects the fact that regulations balance health protection with treatment costs and feasibility. But it does mean that meeting EPA standards doesn't guarantee your water is as safe as it could be. Some states, like California, have adopted stricter standards than the federal requirement, recognizing PCE's particular prevalence in their water systems.

California leads the nation in PCE contamination, with 123 water systems exceeding the EWG guideline. Pennsylvania follows with 56 systems, Massachusetts with 44, New York with 36, and Wisconsin with 22. This geographic pattern isn't random. California's long history of dry cleaning, aerospace manufacturing, and electronics production created widespread contamination. The Northeast's industrial past left similar legacies in Pennsylvania and Massachusetts. These regions also tend to have sandy or permeable soils that allow contaminants to travel quickly to groundwater. If you live in these states — or near any industrial area, military base, or cluster of dry cleaners — your water is at higher risk.

Fortunately, PCE responds well to treatment. Activated carbon filters remove PCE effectively when properly installed and maintained. Reverse osmosis systems remove up to 99.9% of PCE from your drinking water. Air stripping, a technique that bubbles air through water, can also reduce PCE levels significantly. If your water system reports PCE contamination, ask them which treatment method they use. If your home relies on well water, consider having it tested independently — well water isn't regulated like municipal systems. Echo Water's testing services can identify PCE in your water and recommend the right filtration system for your home. Don't assume your water is safe just because it meets EPA standards. Your family deserves protection that matches the best available science.

Regulatory Standards for Tetrachloroethylene (perchloroethylene)

Cities With the Highest Tetrachloroethylene (perchloroethylene) Levels

States Most Affected by Tetrachloroethylene (perchloroethylene)

Frequently Asked Questions

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