The agricultural land-use history of the region and how it maps onto detections
Historic soil fumigant use in VI
In regions like the Virgin Islands, agricultural practices from decades ago included soil fumigants that contained 1,2,3-trichloropropane (TCP) as an impurity. These compounds have a legacy effect, gradually leaching into groundwater and potentially reaching water sources.
Monitoring of public water systems in St. Thomas
The Water & Power Authority serving St. Thomas has been monitored under the EPA’s Unregulated Contaminant Monitoring Rule (UCMR3) during 2013–2015. Four samples were analyzed for 1,2,3-TCP, with all results below the reporting level.
Why 1,2,3-trichloropropane resists air stripping and what that means for treatment choice
Chemical persistence of TCP
1,2,3-TCP is a chlorinated solvent with properties that make it resistant to removal by air stripping methods because it does not easily volatilize into air streams from water.
Implications for choosing equipment
This persistence means that common aeration or simple treatment devices designed for volatile compounds are ineffective for 1,2,3-trichloropropane. Treatment options require technologies capable of adsorbing or chemically neutralizing this contaminant.
How California's 5 ng/L state limit compares with the absence of a federal MCL
No federal maximum contaminant level established
The EPA has not set a maximum contaminant level (MCL) for 1,2,3-TCP, so federal standards do not define a legal limit for this constituent. Detections in water are recorded but not classified as violations.
California’s stringent guidance
California has established a notification level of 5 nanograms per liter (ng/L), or 0.005 micrograms per liter (µg/L), which is a far more stringent advisory than federal sampling thresholds. This highlights the range of regulatory approaches and gives perspective on sensitivity towards 1,2,3-TCP.
What 'detected', 'median' and 'range' mean in the sampling record on this page
Definition of detected in EPA UCMR3 context
A detection means that the analytical instrument measured a concentration at or above the reporting level. For this water system, no samples showed 1,2,3-TCP above the reporting level of 0.03 µg/L (30 parts per trillion).
Median and range are not applicable here
With no reported detections above the reporting limit, median concentrations and ranges are not available from the public water system’s data for 1,2,3-trichloropropane.
What distinguishes this problem from the two problems most often confused with it
Difference from other chlorinated hydrocarbons
1,2,3-TCP differs chemically and behaviorally from related chlorinated solvents such as trichloroethylene (TCE) and perchloroethylene (PCE), which often volatilize easier and respond to different treatment methods.
Distinct from aesthetic water problems
Unlike compounds that affect taste, staining, or corrode plumbing, 1,2,3-TCP is generally odorless and colorless. Its presence requires targeted testing and treatment approaches rather than general water softening or filtration measures.
Choosing household water equipment to address 1,2,3-trichloropropane requires understanding that regional data show no current detections above measurement thresholds in St. Thomas public water. Comprehensive testing is necessary to know your home’s actual water content. The Autotrol 1,2,3-TCP Filter offers a documented technology designed to address this chlorinated solvent effectively, shipping ready to configure for residential use.
This page reviewed the region’s contamination history, chemical properties affecting treatment options, regulatory context, interpretation of monitoring data, and differentiation from similar issues to guide your equipment choice for 1,2,3-TCP concerns.
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