How a Soil Fumigant Impurity from the 1950s-1980s Reached Deep Groundwater Decades Later
1,2,3-trichloropropane, commonly known as 1,2,3-TCP or simply TCP, is a chlorinated solvent historically used as an impurity in soil fumigants mainly applied between the 1950s and 1980s. Over time, TCP migrated through soil layers and entered deep groundwater reserves that supply many public water systems. In Anne Arundel County, Maryland, the Glen Burnie-Broadneck Community Water System (CWS) draws water from groundwater sources affected by this legacy. The delayed transport means substances applied decades ago can still appear in water today, albeit in typically low concentrations.
Why the Reporting Level for This Solvent Is Thousands of Times Lower Than for Common Metals
The federal monitoring program for unregulated contaminants, called UCMR3, measures TCP at a reporting level of 0.03 micrograms per liter (µg/L), equivalent to 0.03 parts per billion (ppb). This extremely low detection threshold reflects concerns about the solvent’s persistence and potential health effects, rather than any regulatory maximum contaminant level (MCL), which does not currently exist for TCP. The reporting level is designed to provide data on occurrence in public water systems, even at trace amounts far below limits set for more common metals. In Anne Arundel County’s Glen Burnie-Broadneck system, twelve samples ranged below this reporting threshold, indicating no detection of TCP at or above the 0.03 µg/L level during 2013-2015 monitoring.
Granular Activated Carbon Contact Time: Why Bed Depth Matters More for TCP Than for Taste
Treatment technologies that address chlorinated solvents like TCP rely heavily on granular activated carbon (GAC) filtration. Unlike contaminants affecting taste or odor, TCP requires sufficient contact time within a deep carbon bed to adsorb effectively. The bed depth controls exposure duration between water and carbon, which is critical because TCP molecules are smaller and less reactive than many taste-related compounds. To ensure adequate treatment, filtration units must provide enough carbon volume and flow control to maximize this contact time, a principle incorporated in specialized Pentair equipment designed specifically for TCP challenges.
How to Compare This Area's Record With a Neighboring County's Without Overreading It
Data from the Glen Burnie-Broadneck system shows no detections of 1,2,3-TCP above the federal reporting level. Nearby counties may report different occurrences due to variations in groundwater geology, historical land use, and agricultural chemical applications. Comparing these records should be done carefully: detection of TCP in one system does not predict specific household water quality in another. Each public water system’s monitoring reflects a broad area and supply source, not individual homes. To ascertain a home's precise TCP level, targeted laboratory testing of the well or tap water is necessary.
The Household or Facility Symptoms That Do and Do Not Point to This Problem
TCP is colorless, odorless, and tasteless at typical environmental concentrations, so household symptoms like unusual smells, discoloration, or taste changes usually do not indicate its presence. If you notice staining, metallic taste, or cloudiness, these water characteristics arise from other issues such as iron, manganese, or hardness minerals. Because TCP is a volatile chlorinated solvent, it does not produce immediate sensory signs. Awareness of TCP presence relies exclusively on analytical testing rather than symptoms.
Decision Pathway Summary: The Glen Burnie-Broadneck public water system serving Anne Arundel County shows no detected 1,2,3-TCP above 0.03 µg/L in federal monitoring. This suggests that TCP is not a widespread concern in the municipal supply, but only specific water tests can establish levels in individual household water. For residential TCP challenges, advanced Pentair filtration units utilizing granular activated carbon provide a proven approach to address this pollutant at the tap, ensuring peace of mind about this legacy chlorinated solvent.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2014-08-06. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for Glen Burnie-Broadneck (MD0020017), MD: 12 results across 1 listed contaminants, 0 detections above the reporting level; nothing detected above the method reporting level
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