Autotrol 1,2,3-TCP Filter

Buy Now

View full details

Granular Activated Carbon Contact Time: Why Bed Depth Matters More for TCP Than for Taste

Longer contact time enhances TCP interaction with carbon

1,2,3-TCP is a chlorinated solvent with chemical properties that make it less reactive than many taste-related compounds. When passing through a granular activated carbon (GAC) filter, sufficient contact time—achieved by the bed depth of the carbon—is crucial for effectively addressing this constituent. The deeper the carbon bed, the more opportunity for TCP molecules to adsorb onto the media, which is especially important when existing household equipment cannot fully keep pace with treatment needs.

Short contact times may still address taste but miss TCP

While shallower carbon beds might improve taste and odor quickly, they often lack the capacity or contact time to address 1,2,3-trichloropropane adequately. Households noticing persistent TCP-related water issues despite operational equipment might require technology offering increased carbon bed depth or enhanced contact configurations.

How California's 5 ng/L State Limit Compares with the Absence of a Federal MCL

Federal monitoring detected TCP below 0.03 µg/L (30 ng/L)

Between 2013 and 2015, the Salt Lake City Water System—which delivers surface water to over 380,000 residents—underwent EPA's Unregulated Contaminant Monitoring Rule (UCMR3) testing for 1,2,3-trichloropropane. None of the 33 tested samples showed TCP concentrations at or above the reporting level of 0.03 micrograms per liter (µg/L), equivalent to 30 parts per trillion (ppt).

California’s more stringent 5 ng/L (0.005 µg/L) limit is voluntary locally

Though California has set a state-level maximum contaminant level (MCL) of 5 nanograms per liter (0.005 µg/L) for TCP, no federal MCL exists at this time. Salt Lake City's public water system has no EPA health-based violations related to 1,2,3-TCP on record, as the federal threshold for enforceable limits is not yet defined.

The Agricultural Land-Use History of the Region and How It Maps onto Detections

Legacy fumigants linked to 1,2,3-trichloropropane in surface and groundwater

1,2,3-trichloropropane historically appeared as an impurity in soil fumigants used in agricultural regions. Salt Lake County’s surface water supply is not known for high agricultural TCP sources compared to some other areas, which aligns with the UCMR3 results showing no detections above reporting levels during 2013–2015.

Current detections reflect regional and system-wide water quality, not individual homes

Government-collected data represent the public system's water quality and do not specify any home's water status. A household equipped with existing treatment devices that works but struggles to keep up should test their own water directly for TCP and related constituents to personalize water management strategies.

Why Aesthetic Secondary Standards Differ from Health-Based Limits, Applied to This Constituent

Chlorinated solvents like TCP have no established secondary aesthetic limits

Aesthetic secondary standards typically cover parameters such as taste, color, or corrosion-related chloride levels. TCP, being a chlorinated solvent, does not fall under these aesthetic parameters. Thus, the lack of a federal MCL or secondary standard should not be conflated with water being unsafe or violating taste and odor guidelines.

Exceeding aesthetic thresholds does not apply to 1,2,3-trichloropropane

Because TCP is not governed by secondary aesthetic thresholds, no statement about taste or staining applies. Concerns over this constituent relate to potential health considerations and therefore involve health-based limits, which are still under discussion and development at the federal level.

What a Certified Laboratory Test for This Constituent Reports and How to Read It

Laboratory results specify micrograms per liter (µg/L) or parts per billion (ppb)

Testing for 1,2,3-trichloropropane in household water requires a certified laboratory. The report shows the concentration in micrograms per liter (µg/L), which is equivalent to parts per billion (ppb). Any amount reported is an instrumental detection and does not itself indicate a violation or safety concern without regulatory benchmarks.

Detection levels depend on laboratory method sensitivity

Laboratories use specialized methods capable of detecting TCP at very low concentrations, often below federal reporting levels. Understanding the laboratory’s detection limit helps interpret whether a reported number reflects a confirmed presence and how it compares to known area-wide monitoring data.

What You Should Not Conclude from Area Data

Salt Lake City's public water system record from EPA monitoring indicates no detected 1,2,3-trichloropropane at or above the 0.03 µg/L reporting level in 33 samples between 2013 and 2015. This regional data does not guarantee the absence of TCP in any individual household’s water. It also does not indicate a health violation or unsafe condition. Households with existing equipment that cannot keep up may consider specialized treatment options designed to address TCP, such as technology featuring enhanced granular activated carbon contact time, including the Autotrol 1,2,3-TCP Filter, which ships ready to configure for household use.

Where this information comes from

Source: EPA SDWIS public water system record. Sampled 2014-01-06. These figures describe the public water system's record, not the plumbing inside any individual building.

On record: EPA UCMR3 monitoring (2013-2015) for Salt Lake City Water System (UTAH18026), UT: 33 results across 1 listed contaminants, 0 detections above the reporting level; nothing detected above the method reporting level