How a Soil Fumigant Impurity from the 1950s-1980s Reached Deep Groundwater Decades Later
1,2,3-trichloropropane, often abbreviated as TCP, is a chlorinated solvent historically used as an impurity in soil fumigants between the mid-20th century decades. Though discontinued, its chemical stability allowed it to persist in the environment, migrating slowly downward to contaminate groundwater over time. This delayed movement means that contamination can appear in surface or groundwater even decades after last applications ceased.
In the St. Charles area of St. Louis County served by MO American Water Co., federal sampling under the EPA’s Unregulated Contaminant Monitoring Rule (UCMR3) between 2013 and 2015 found no measurable detection of 1,2,3-TCP above the reporting limit of 0.03 micrograms per liter (µg/L). This limit corresponds to 0.03 parts per billion (ppb), a very low concentration threshold used for monitoring emerging contaminants.
The Household or Facility Symptoms That Do and Do Not Point to This Problem
Because 1,2,3-trichloropropane is colorless and odorless, it does not cause sensory changes to water such as taste or smell differences that would be noticeable to residents. Therefore, household symptoms like unpleasant odors, discoloration, or staining are unlikely indicators of TCP presence.
Health-based violations for this constituent are not recorded in the area's public water system, indicating no regulatory concern with toxicity at detected levels. Thus, common water use symptoms such as cloudiness, staining, or corrosion typically observed with other contaminants are not characteristic of TCP.
The Agricultural Land-Use History of the Region and How It Maps onto Detections
St. Louis County includes regions historically used for agriculture where fumigant application was common, which explains why the EPA monitors 1,2,3-TCP in local water systems. Although TCP originated as an impurity in soil fumigants used decades ago, the lack of detections above reporting levels in the public water system suggests limited or no current impact on surface water sources serving the community.
This monitoring data does not reflect individual household wells, which may have different exposure risks depending on location and groundwater flow. Monitoring records for MO American Water Co. cover the extensive surface water sources and connections in the system.
Which Fixtures, Appliances or Processes Are Affected First and Why
Given the absence of detectable TCP in the public water supply, no household fixtures or appliances are known to be affected specifically by this compound at the system level. TCP’s chemical properties do not cause typical aesthetic or operational issues seen with other contaminants.
Households weighing treatment options for 1,2,3-TCP typically consider systems designed to address chlorinated solvents overall. These systems are configured to reduce trace TCP where testing confirms its presence, focusing on filtration methods appropriate for volatile or semi-volatile organic compounds.
What Changes for a Large Household, a Second Home, or a Seasonal Property
In larger households or those with higher water use, consistent treatment capacity is important if testing finds TCP at measurable levels. Conversely, seasonal properties with intermittent use may preserve filtration media effectiveness longer due to reduced flow.
Because no TCP was detected in the St. Charles public supply record, decisions about treatment configurations should be based on specific well water testing per property. Treatment options can be purchased ready to configure to each household’s needs.
One documented approach for managing 1,2,3-trichloropropane when detected is the Autotrol 1,2,3-TCP Filter. This equipment technology, purchased direct, is designed to address this chlorinated solvent through advanced filtration suited to household water systems.
Summary and Source Reference
Sampling data from the MO American Water Co. public water system serving St. Charles and St. Louis County shows no detections of 1,2,3-trichloropropane above 0.03 µg/L during the 2013–2015 federal UCMR3 survey. No health-based violations have been recorded. This information pertains to the public system and does not substitute for individual water testing.
For further details, consulting the EPA Safe Drinking Water Information System (SDWIS) database provides public records on contaminant occurrence and compliance status in your area.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2013-11-06. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for MO American Water Co. - St. Louis County (MO6010716), MO: 20 results across 1 listed contaminants, 0 detections above the reporting level; nothing detected above the method reporting level