According to EPA public water system records for Rapides Parish, Louisiana, the City of Alexandria water system, which serves over 66,000 people through more than 22,000 connections, reported zero detections of 1,2,3-trichloropropane (1,2,3-TCP) above the reporting threshold of 0.03 micrograms per liter (µg/L), or 0.03 parts per billion (ppb), in a set of 20 samples taken during 2013-2015 as part of the federal Unregulated Contaminant Monitoring Rule (UCMR3).
Granular activated carbon contact time: why bed depth matters more for TCP than for taste
The chlorinated solvent known as 1,2,3-trichloropropane is a synthetic compound once used in industrial applications and as a soil fumigant impurity. Its chemical properties make it more challenging to address than common taste or odor concerns, which are often managed by aesthetic standards rather than health-based limits.
Granular activated carbon (GAC) technology is an effective treatment method for removing or reducing 1,2,3-TCP concentrations. A critical parameter in GAC efficacy is contact time—the duration water spends exposed to the carbon bed. For 1,2,3-TCP, longer contact times enabled by deeper carbon beds are more important because this contaminant adsorbs more slowly compared to compounds causing taste or odor issues. This means that properly configured carbon beds can address TCP at levels relevant to residential use, even if the water tastes normal.
How many samples and wells stand behind the figures, and what a small sample means
The City of Alexandria’s water system samples come from groundwater sources, which can vary significantly depending on local geology and human activities. The 20 samples mentioned reflect a limited snapshot collected over approximately six months. While no detections above 0.03 µg/L were reported, this small sample size cannot rule out occasional presence of 1,2,3-trichloropropane in any individual well or household supply. Sampling results are system-wide metrics, not direct readings of any single tap.
How to judge treatment capacity against the household's or facility's daily demand
When considering a treatment device designed to address 1,2,3-TCP, it is important to size the system's capacity in line with your household’s daily water consumption. Systems that use granular activated carbon must contain enough media volume to maintain effective contact time at higher flow rates. A treatment unit that ships ready to configure can be matched to your typical water use patterns, ensuring sufficient contact time to address chlorinated solvents like TCP without compromising water availability.
Why aesthetic secondary standards differ from health-based limits, applied to this constituent
Government water quality guidelines distinguish between health-based maximum contaminant levels (MCLs) and secondary standards aimed at aesthetics such as taste, odor, and staining. For 1,2,3-TCP, no federal MCL currently exists. This means that detections in this area’s water do not reflect violations or unsafe conditions but are monitored as part of an unregulated contaminant program. Secondary standards primarily affect substances like chloride or total dissolved solids, which influence taste and corrosivity, and do not govern TCP.
What 'detected', 'median' and 'range' mean in the sampling record on this page
A detection indicates that an instrument measured the presence of a substance above a reporting level; it is not a health finding. In this record for Rapides Parish, no 1,2,3-TCP results were reported above the 0.03 µg/L threshold, so terms like median or range are not applicable for detected levels. This highlights that the monitoring program identified a non-detect result for this chlorinated solvent in the sampling period.
Which fixtures, appliances or processes are affected first and why
In homes where 1,2,3-TCP might be present, the whole water supply can carry the compound since it is dissolved in the source water. However, drinking water fixtures such as kitchen faucets and water dispensers are the most immediate points of contact. Appliances that rely on water, such as ice makers and coffee machines, also interact directly with any contaminants. Because TCP is chemically stable, it can persist through plumbing without breaking down, making point-of-entry or point-of-use treatment units that use granular activated carbon an effective choice.
The best single step to determine your household water’s 1,2,3-TCP level is to order a laboratory water test specifically for 1,2,3-trichloropropane. This test will provide a precise concentration for your residence, which municipal or regional data cannot specify. Knowing your own measurement allows you to evaluate if the Pentair 1,2,3-TCP Filter, a ready-to-configure system designed for residential water treatment, is appropriate for addressing any detected levels of this chlorinated solvent in your water supply.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2015-08-13. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for City of Alexandria (LA1079001), LA: 20 results across 1 listed contaminants, 0 detections above the reporting level; nothing detected above the method reporting level
- ✓ 90-Day Money-BackNo restocking fees — return within 90 days.
- ✓ Manufacturer WarrantyGenuine Fleck · Pentair · VIQUA equipment.
- ✓ Free Expert SizingTalk to a specialist and buy the right system the first time.