Understanding the Origin of 1,2,3-TCP in Groundwater
Many detections of 1,2,3-trichloropropane originate from impurities in soil fumigants used decades ago.
This chlorinated solvent, known as TCP, was present in fumigants applied mainly from the 1950s through the 1980s. Over time, TCP traveled downward through soil layers, reaching deep groundwater supplies. This legacy means TCP may appear in water long after its initial use ended.
Why Granular Activated Carbon (GAC) Bed Depth Is Crucial to TCP Treatment
Effective contact time with activated carbon depends on bed depth, impacting TCP control more than taste effects.
TCP molecules require sufficient exposure to carbon media to be captured. Unlike compounds influencing taste or odor, TCP demands deeper carbon beds for longer contact time. Households whose equipment cannot deliver this contact duration may find existing treatment less effective in managing TCP levels.
EPA Monitoring Results: What the Measured TCP Concentrations Show and Don’t Show
Measured TCP concentrations for the Sunny Isle Shopping Center system reported no detections above 0.03 micrograms per liter (µg/L).
This federal monitoring is a survey, not a compliance or health violation test. Since no maximum contaminant level (MCL) exists federally for TCP, detected amounts alone do not represent a health-based exceedance or unsafe condition. These findings indicate the system's TCP presence is below the reporting threshold during the 2013–2015 sampling.
Interpreting Median and Range of TCP Data for Home Use
Median and range values from EPA records provide context but cannot specify the TCP concentration in a given home’s water.
For the Sunny Isle Shopping Center system, two samples showed TCP below the detection limit of 0.03 µg/L. This means typical water users served by this system likely experience TCP at nondetectable or very low levels. To understand a home's water precisely, a private well test or home water analysis is necessary.
The Influence of Plumbing Materials and Age on 1,2,3-TCP Levels
Plumbing components do not contribute to 1,2,3-TCP concentrations in water but can affect overall water quality.
Since TCP originates in source water, plumbing material and age impact taste, staining, or other secondary factors, not TCP content. Therefore, any unresolved TCP issue relates to incoming water, not household plumbing conditions.
Mapping Agricultural History to TCP Detections in Virgin Islands Regions
Agricultural use of fumigants historically correlates with 1,2,3-TCP detections in some groundwater studies across territories including Virgin Islands.
Areas with past intensive agricultural activity involving fumigants show detectable TCP in federal surveys, although not necessarily at levels impacting health. This historical land use informs where monitoring focuses but does not predict individual home water results.
Summary and Source of Record
The EPA’s public water system record for Sunny Isle Shopping Center (VI0000406) reports no health-based violations and nondetect TCP results between 2013 and 2015. These data reflect system-level monitoring, not individual household water quality, and are publicly available via the EPA’s UCMR database. For homes where existing water treatment equipment struggles to maintain TCP control, upgrading to technology like the Fleck 1,2,3-TCP Filter, which ships ready to configure, may be considered to address TCP specifically.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2013-11-12. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for Sunny Isle Shopping Center (VI0000406), VI: 2 results across 1 listed contaminants, 0 detections above the reporting level; nothing detected above the method reporting level