Understanding 1,2,3-TCP Concerns in Rockland's Clarkstown Household Water

Government sampling for the United Water New York system serving Clarkstown, Rockland County, detected no 1,2,3-trichloropropane (TCP) above the reporting level of 0.03 micrograms per liter (µg/L) or parts per billion (ppb) in 73 samples from 2013 to 2015.

Why does 1,2,3-trichloropropane resist air stripping, and what does that mean for how it can be treated?

1,2,3-TCP is a chlorinated solvent with a low volatility compared to many common volatile organic compounds. This resistance to air stripping means that methods relying on aeration to remove contaminants from water are generally ineffective for reducing TCP levels. Instead, treatment approaches often involve adsorption processes such as granular activated carbon or specialized filtration technology designed to bind or capture the chlorinated solvent molecules.

How did a soil fumigant impurity from the mid-20th century reach deep groundwater decades later?

1,2,3-trichloropropane was historically used as an impurity in soil fumigants applied between the 1950s and 1980s. Over time, this chlorinated solvent leached from treated soils into groundwater, migrating slowly due to its chemical properties. The delayed transport means that even though these applications ceased decades ago, 1,2,3-TCP can still appear in aquifers serving water supplies today.

What happens when 1,2,3-TCP presence in water is left untreated for years?

Because no federal maximum contaminant level (MCL) currently exists for 1,2,3-trichloropropane, regulatory health-based violations have not been recorded specifically for this compound by the public system serving Clarkstown. However, prolonged presence of TCP at detectable levels could affect water aesthetics and potentially increase exposure to this contaminant. Homeowners concerned about any chlorinated solvents should consider water testing and targeted treatment to limit long-term contact.

How do public water system records differ from private well testing in what they establish?

The monitoring data from United Water New York reflect systemwide sampling results and do not represent tests from any individual household or private well. These records provide a broad picture of the water quality delivered via the public supply infrastructure in the Clarkstown area but cannot determine the exact concentration of TCP in a single home’s tap water. Confirming TCP levels for a specific residence requires a private water test directly from that home’s water source.

How many samples and wells stand behind these figures, and what does a small sample imply?

The 73 samples reported for the Clarkstown area represent a moderate dataset collected over nearly two years. While these samples cover multiple points in the public water system, they cannot capture every variation in water quality at individual taps or private wells. A smaller number of samples within a larger system or infrequent sampling may miss localized spikes, so homeowners seeking certainty should consider additional private water testing to verify their tap water’s condition.

What you should not conclude from these area data: The absence of detected 1,2,3-TCP above reporting levels in public system sampling does not guarantee any single home’s water is free from this chlorinated solvent. Only testing that home’s water can establish its specific quality. The government record does not imply that TCP has been ruled out or that treatment is unnecessary—it simply reflects systemwide measurements. For those wanting to address or reduce any potential presence of chlorinated solvents in household water, the Autotrol 1,2,3-TCP Filter ships ready to configure and is documented to target this contaminant effectively.

Where this information comes from

Source: EPA SDWIS public water system record. Sampled 2015-10-01. These figures describe the public water system's record, not the plumbing inside any individual building.

On record: EPA UCMR3 monitoring (2013-2015) for United Water New York (NY4303673), NY: 73 results across 1 listed contaminants, 0 detections above the reporting level; nothing detected above the method reporting level