Whole House 1,2,3-TCP Reduction Water Filter System - Trichloropropane Removal
What to Know About 1,2,3-Trichloropropane in Westerly’s Public Water System and Treatment Limits
Government sampling of the Westerly Water Department in Washington County, Rhode Island, which serves over 35,000 people using groundwater sources, found no detections of 1,2,3-trichloropropane (TCP) above the reporting level of 0.03 micrograms per liter (µg/L or parts per billion). This means that during the federal Unregulated Contaminant Monitoring Rule (UCMR3) testing from 2013 to 2015, TCP was not measurable above this low threshold in public system water. While this data shows no indication of TCP presence at these levels in community water, it does not speak directly to individual household water quality or possible private well conditions.
Why 1,2,3-Trichloropropane Resists Air Stripping and What That Means for Treatment Choice
1,2,3-trichloropropane is a chlorinated solvent that is not easily removed by air stripping. This resistance occurs because TCP has chemical properties that keep it dissolved in water rather than volatilizing into air readily. Therefore, treatment methods relying on air stripping are often ineffective against this contaminant. Instead, alternative technologies that target TCP’s chemical structure directly, such as granular activated carbon adsorption with adequate contact time, provide more reliable removal for affected water supplies.
How California’s 5 Nanogram per Liter Limit Compares with the Absence of a Federal MCL
California has set a state limit for 1,2,3-TCP at 5 nanograms per liter (ng/L), equivalent to 0.005 µg/L, which is extremely low compared to typical detection levels and much lower than any federal maximum contaminant level (MCL)—because the EPA has not established a federal MCL for TCP. The EPA’s lack of a federal safety standard means federal regulatory limits do not apply for TCP in public water. However, some states like California apply their own precautionary limits. This difference highlights the importance of understanding local regulations and testing your own water to determine if treatment adjustments are needed.
Granular Activated Carbon Contact Time: Why Bed Depth Is More Important for 1,2,3-TCP than for Taste Issues
Granular activated carbon (GAC) is effective for adsorbing chlorinated solvents like 1,2,3-trichloropropane, but success depends heavily on contact time between water and the carbon bed. For TCP, longer contact time—achieved through greater bed depth—is critical to allow the carbon to capture this contaminant efficiently. This contrasts with treatment primarily aimed at taste or odor compounds, which often require less contact time. Therefore, selecting equipment designed with sufficient carbon bed depth is essential for addressing TCP in water.
The Role of Plumbing Material and Age, Separate from the Source Water
Plumbing materials and the age of household pipes can affect water quality independently from the water source. Older plumbing may leach metals or affect certain aesthetic qualities, but it does not influence the presence of 1,2,3-trichloropropane, which originates from the water source itself. Understanding this distinction helps clarify that issues with TCP require treatment targeting the water supply's chemistry, not the piping.
How a Soil Fumigant Impurity from Decades Ago Reached Deep Groundwater
1,2,3-trichloropropane entered groundwater primarily as an impurity in soil fumigants used in agriculture from the 1950s through the 1980s. Due to its persistence and solubility, this chlorinated solvent migrated downward, slowly reaching deep groundwater over many years. This delayed migration explains why TCP may still be detected in water supplies long after its original application ceased, necessitating ongoing attention to treatment options.
The Order to Rule Out Causes, From Cheapest Checks to Laboratory Testing
If your existing water treatment equipment targeted TCP but has failed, start by checking operational factors like flow rates, carbon replacement schedules, and system integrity. Next, consider testing your water through a certified laboratory for 1,2,3-trichloropropane specifically, since local public water data cannot guarantee the absence of TCP in your home. Testing private well water or your household supply independently establishes actual contaminant levels. This step is crucial before deciding on replacement or upgrades.
After confirming presence and concentration, treatment options that rely on granular activated carbon with sufficient contact time are well-documented to address 1,2,3-trichloropropane effectively. The C-Series 1,2,3-TCP Filter ships ready to configure for residential use and is designed specifically to target this chlorinated solvent.
In summary, public data show no detectable 1,2,3-trichloropropane in Westerly’s system, but individual water quality requires testing to confirm. Since TCP resists air stripping, granular activated carbon systems with adequate bed depth offer a documented path forward for treatment if needed.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2015-09-16. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for Westerly Water Department (RI1559512), RI: 14 results across 1 listed contaminants, 0 detections above the reporting level; nothing detected above the method reporting level