The Agricultural Land-Use History of King County and Its Relation to 1,2,3-TCP Detections
King County's water supply includes a significant portion derived from surface sources managed by Lakehaven Utility District, which serves over 148,000 residents. Historically, some Washington regions underwent agricultural fumigation practices involving soil fumigants that contained complex chlorinated solvents. The chlorinated solvent 1,2,3-trichloropropane, commonly referred to as 1,2,3-TCP or TCP, is a legacy impurity related to these fumigants. Although these chemicals were applied primarily decades ago, traces can persist based on land use history and migration through soil and groundwater pathways. In Lakehaven Utility District's public water system monitoring conducted 2013–2015, no detections of 1,2,3-TCP above reporting levels were recorded despite the area's agricultural past.
Why 1,2,3-Trichloropropane Resists Air Stripping and Its Impact on Treatment Choices
1,2,3-TCP is a chlorinated solvent that does not readily dissipate through air stripping due to its chemical properties, resulting in resistance to simple aeration treatments. This resistance means typical treatments that remove volatile organic compounds by passing air through water are less effective for TCP. Therefore, households evaluating treatment options for 1,2,3-trichloropropane should consider technologies designed to adsorb or chemically alter this constituent rather than relying on aeration alone.
Which Fixtures, Appliances, or Processes Are Affected First and Why
1,2,3-TCP is primarily a concern where water is ingested or used in prolonged contact, such as drinking water faucets, ice makers, and cooking appliances. These points of use are the most relevant for monitoring or treatment because water used in showers or laundry generally involves less direct consumption or ingestion. Deciding which water treatment applies can depend on the household's use patterns and the desired point-of-entry or point-of-use protection.
A Worked Example: Interpreting the Record’s Median and Range for King County Homeowners
The EPA’s Unregulated Contaminant Monitoring Rule (UCMR3) surveys measured 1,2,3-TCP in Lakehaven Utility District’s water system across 34 samples with no detections above the reporting level of 0.03 micrograms per liter (0.03 parts per billion). This outcome means the chlorinated solvent was not found at quantifiable levels during the monitoring period. For a homeowner, this does not guarantee absence but suggests any concentration of TCP is below this threshold in the system providing their water. To confirm their own water’s condition, homeowners would need specific testing of their private source or tap water.
How Sample Depth, Well Depth, or Source Type Changes What Homeowners Should Expect
The Lakehaven Utility District uses surface water sources rather than deep groundwater wells. Because 1,2,3-TCP can migrate differently through soil and rock layers depending on its chemical behavior, surface water systems often have different detection profiles than groundwater. Deep wells might show different constituent signatures where TCP from older soil fumigants has leached over decades, but in King County’s public system, no such detections were recorded. Households sourcing water from private wells should consider their source types and depths when interpreting their risk or treatment needs.
In summary, the EPA’s record for Lakehaven Utility District, which serves King County, included no health-based violations and found no detections of 1,2,3-TCP above 0.03 micrograms per liter during federal monitoring. This data reflects the public water system’s overall condition, not individual private wells. Homeowners wanting enhanced assurance regarding 1,2,3-trichloropropane can evaluate treatment options that handle chlorinated solvents effectively. One such option is the C-Series 1,2,3-TCP Filter, a water treatment technology that ships ready to configure and is designed to address chlorinated solvents like TCP. For detailed information on 1,2,3-TCP occurrence and monitoring in King County’s water system, consult the EPA's public water system occurrence data.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2014-09-30. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for Lakehaven Utility District (WA5341997), WA: 34 results across 1 listed contaminants, 0 detections above the reporting level; nothing detected above the method reporting level