Fleck 1,2,3-TCP Filter

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How a Soil Fumigant Impurity from the 1950s-1980s Reached Deep Groundwater Decades Later

Legacy use of 1,2,3-trichloropropane in soil fumigation

1,2,3-Trichloropropane, also called TCP, was used historically as an ingredient or impurity in soil fumigants between the 1950s and 1980s. These chemicals were applied to agricultural fields to control pests.

Slow movement into groundwater

Over time, TCP has leached through soils, slowly migrating into deep groundwater sources. This process can take decades because TCP is persistent and does not easily break down or volatilize once it reaches subsurface water.

Sampling shows presence but no federal limit violation

Government sampling by the EPA in the Virgin Islands’ Water & Power Authority public water system found no detections of 1,2,3-TCP above 0.03 micrograms per liter (µg/L, or parts per billion). This reporting level is important for understanding what was measured but is not a safety threshold.

Why 1,2,3-Trichloropropane Resists Air Stripping and What That Means for Treatment Choice

Chemical properties of TCP impact treatment

1,2,3-TCP behaves differently than many common volatile organic compounds. Unlike chemicals easily removed by air stripping, TCP’s low volatility and chemical stability make it resistant to such treatment.

Implications for household water treatment

This resistance means that standard aeration-based systems often cannot reduce TCP to lower levels. Homeowners whose current treatment equipment struggles may require specialized technology to address this constituent effectively.

The Agricultural Land-Use History of the Region and How It Maps onto Detections

Historical agricultural practices in the Virgin Islands

The agricultural history of the Virgin Islands reflects use of soil fumigants with TCP impurities. Although current water provided by the Water & Power Authority shows no detections over the reporting limit in recent studies, legacy impacts vary across locations.

Correlation between land use and localized TCP presence

Areas with past intensive agriculture may experience different water quality profiles. However, the overall public water system records show no health-based violations concerning TCP.

Which Fixtures, Appliances or Processes Are Affected First and Why

Household water uses sensitive to TCP presence

Faucets and appliances that use water directly for consumption or food preparation are most relevant for considering TCP. Although the system-wide testing shows no quantifiable presence, any ongoing minor levels may be more noticeable in drinking and cooking taps.

Why existing equipment might not keep up

Systems designed without consideration for chlorinated solvents like TCP may experience declining performance or incomplete treatment. This can leave taps delivering water with small residuals of 1,2,3-trichloropropane.

What a Certified Laboratory Test for This Constituent Reports and How to Read It

Testing methods and reporting levels

Laboratories use sensitive instruments capable of detecting TCP at parts per billion levels, typically reporting results in micrograms per liter. The EPA’s reporting level for TCP in this area is 0.03 µg/L.

Interpreting non-detections and detections

A result of 'non-detected' indicates the concentration was below 0.03 µg/L but does not guarantee complete absence. Conversely, detection above this level indicates presence but not a violation or unsafe condition.

A Worked Example: Reading the Record's Median and Range as a Homeowner Would

Understanding EPA UCMR3 sampling in your water system

Sampling from 2013 to 2015 in the Water & Power Authority system included four measurements of 1,2,3-trichloropropane, all below the reporting limit of 0.03 µg/L. There is no median value above zero, indicating that no quantifiable TCP was found during that period.

What this means for your household water

Since these results reflect the entire public water supply, individual home well or tap concentrations may differ and require specific water testing. Given that existing equipment may be challenged by TCP’s chemical properties, upgrading to technology such as the Fleck 1,2,3-TCP Filter, which ships ready to configure, can be a prudent step.

The EPA data referenced here represents the public system results and not a specific home's water quality. To confirm your own water’s TCP levels, consult a certified laboratory test. For further details, the EPA's Safe Drinking Water Information System (SDWIS) public water system record for Water & Power Authority (St. Thomas) is the official source.

Where this information comes from

Source: EPA SDWIS public water system record. Sampled 2014-11-05. These figures describe the public water system's record, not the plumbing inside any individual building.

On record: EPA UCMR3 monitoring (2013-2015) for Water & Power Auth. (St. Thomas) (VI0000443), VI: 4 results across 1 listed contaminants, 0 detections above the reporting level; nothing detected above the method reporting level