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

1,1-Dichloropropene is a synthetic chemical that doesn't occur naturally in the environment. It belongs to a family of chlorinated compounds often used as soil fumigants — chemicals applied to agricultural land to kill pests, fungi, and weeds before planting. It can also appear as a breakdown product of other chlorinated solvents used in industrial settings. When these chemicals are applied to soil or disposed of improperly, they can seep into groundwater and eventually reach drinking water systems.

Right now, 16 water systems across the country have detected 1,1-dichloropropene in their supplies. The average level found is 0.147 parts per billion (ppb), with the highest recorded measurement reaching 0.5 ppb. The good news: none of these systems currently exceed established health guidelines. That said, detected doesn't mean harmless, and it's worth understanding what this chemical can do at higher exposure levels.

Research on 1,1-dichloropropene points to liver and kidney damage as the primary concerns with long-term exposure. Animal studies have also shown it may affect the lungs and act as a possible carcinogen — meaning it could raise cancer risk over time. The EPA classifies it as a Group C possible human carcinogen based on animal evidence. At the low levels currently detected in drinking water, the immediate risk appears minimal. But health-conscious families are right to pay attention, especially since children and pregnant women tend to be more sensitive to chemical exposures than healthy adults.

The EPA has set a maximum contaminant level (MCL) of 0.5 ppb for 1,1-dichloropropene in public drinking water — which is also the highest level detected in the data above. The fact that no systems exceed this limit is encouraging. However, the EPA's legal limits are not always the same as what scientists consider truly safe for long-term health. The Environmental Working Group (EWG) often recommends stricter guidelines based on more recent research, and filtration remains a practical option for anyone who wants an extra layer of protection beyond regulatory compliance.

Geographically, Alabama accounts for the largest share of detections, with 10 of the 16 affected water systems located there. New York follows with 3 systems, and South Carolina, Georgia, and Nebraska each report 1 detection. Alabama's agricultural activity — particularly the use of soil fumigants on crops like peanuts, soybeans, and cotton — likely explains why the state leads in detections. Nebraska's presence on the list fits a similar pattern, given its heavy row-crop farming. New York's detections may point more toward industrial solvent contamination near older manufacturing sites. Each region tells a slightly different story about how this chemical enters the water supply.

If you want to reduce your family's exposure to 1,1-dichloropropene, reverse osmosis filtration is your most effective option. Reverse osmosis (RO) systems push water through a semi-permeable membrane that blocks contaminants at the molecular level, removing up to 99% of chlorinated compounds like this one. Activated carbon filters also provide meaningful reduction, particularly when paired with RO. Echo Water's filtration systems use both technologies together, giving you thorough protection against a wide range of chemical contaminants — not just this one. If you're in Alabama or another affected state, it's worth testing your water first to understand exactly what you're dealing with before choosing a filter. Knowing your baseline is always the smartest starting point.

Regulatory Standards for 1,1-Dichloropropene

Cities With the Highest 1,1-Dichloropropene Levels

States Most Affected by 1,1-Dichloropropene

Frequently Asked Questions

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