1,2-Dichloroethylene
trans-DCE·Affects liver, kidneys
The trans isomer of 1,2-DCE, primarily a breakdown product of trichloroethylene and tetrachloroethylene in groundwater. Indicates a larger chlorinated solvent plume nearby.
trans-DCE
EPA limit
0.1 mg/L (MCL)
Most at risk
Households near industrial sites, dry cleaners, or known TCE/PCE plumes
Found in
City water · Well water · Industrial areas
AquaOx filters
YesActivated coconut shell carbon
What it does to you
Health effects
trans-1,2-DCE primarily affects the liver and the kidneys. Animal studies show modest liver enzyme changes and immune system effects at chronic doses. It is generally considered less toxic than its cis isomer, which is why the EPA MCL is set higher at 100 ppb versus 70 ppb for cis-DCE.
The EPA has not classified trans-1,2-DCE for carcinogenicity. Toxicological data is limited compared with parent solvents like TCE and PCE.
Like other chlorinated VOCs, the compound is volatile and contributes to inhalation exposure during hot showers and dishwashing in addition to drinking water ingestion.
Where it comes from
How it gets into your water
trans-1,2-DCE rarely originates from direct industrial discharge. It almost always appears as a microbial breakdown product of more dangerous parent solvents: tetrachloroethylene (PCE) and trichloroethylene (TCE). When those compounds reach anaerobic groundwater, soil bacteria progressively dechlorinate them, and 1,2-DCE is one of the intermediate products.
If trans-1,2-DCE shows up in your water, there is almost certainly a larger TCE or PCE plume nearby. Common upstream sources include dry cleaners, metal degreasing operations, electronics manufacturing, and former industrial waste sites.
Industrial sites
Breakdown of TCE in groundwater
Dry cleaners
Breakdown of PCE in groundwater
Contaminated wells
Often paired with detectable TCE/PCE
Underground tanks
Legacy solvent storage leaks
Find out for yourself
Is it in your water?
trans-1,2-DCE is EPA-regulated, so all community water systems must test for it and report results on the Consumer Confidence Report. If you see it on your CCR, look closely for nearby detections of TCE or PCE because trans-DCE is a marker for the parent compounds.
Private well owners in industrial corridors, near current or former dry cleaners, or within range of a Superfund site should request a full VOC panel that includes trans-1,2-DCE, cis-1,2-DCE, TCE, and PCE together. State drinking-water programs maintain maps of known plume sites.
The fix
How AquaOx filters it
Activated carbon is the standard treatment for chlorinated solvents including trans-1,2-DCE. The Centaur catalytic carbon and coconut shell carbon stages in The AquaOx adsorb the compound as water passes through.
For homes on a known TCE or PCE plume, we recommend pairing The AquaOx whole-home system with the under-sink RO at the kitchen tap to add a second-stage polish on drinking and cooking water.