1,2,3-TCP in Pennington County: Understanding Regional Water Sampling and Treatment Options

If you notice an unusual taste or are investigating the presence of 1,2,3-trichloropropane (TCP) at a faucet in Rapid City, you might be weighing technical approaches to address any concerns. Understanding what federal sampling data says about your area's water, and what it does not say, is a first step.

How Does the Agricultural Land-Use History of Pennington County Relate to 1,2,3-TCP Detections?

Between the 1950s and 1980s, certain soil fumigants used in agriculture included impurities such as 1,2,3-trichloropropane, a chlorinated solvent sometimes abbreviated as TCP. In Pennington County, SD, where Rapid City draws its municipal water from surface water sources, historical agricultural practices can influence the presence of such compounds in groundwater or surface supplies. However, local EPA data from 2013-2015, gathered under the Unregulated Contaminant Monitoring Rule (UCMR3), found no detections of 1,2,3-TCP above the reporting level of 0.03 micrograms per liter (µg/L), equal to 0.03 parts per billion (ppb), in the public water system serving Rapid City.

What Does It Mean That a Chlorinated Solvent From Decades Ago Can Reach Water Sources Today?

The slow migration of chlorinated solvents like 1,2,3-TCP from historical agricultural use into water supplies can take many years, as these compounds may move through soil and rock layers into deeper groundwater or contaminate surface water. In Rapid City's case, water is supplied from surface sources, which are influenced by watershed conditions and can vary seasonally. The absence of detected 1,2,3-TCP in federal monitoring suggests that, for now, this legacy issue is not measurable in the municipal supply at concentrations above laboratory reporting limits.

How Many Water Samples and Wells Support the 1,2,3-TCP Findings for This Area?

The Rapid City community water system was monitored during the 2013-2015 UCMR3 federal sampling period, which included 24 sample results over roughly nine months. None of these samples showed 1,2,3-trichloropropane above 0.03 µg/L. This sample size, while limited, supports a regional snapshot rather than a comprehensive analysis of every connection or private well. Households should consider testing their own water if concerned, as individual well conditions and plumbing materials can differ.

What Additional Questions Might Commercial or Industrial Operators Have Compared to a Household?

Commercial or industrial facilities often require more extensive water quality data to meet process standards or regulatory compliance. They may need frequent repeat testing for 1,2,3-TCP and other chlorinated solvents, consider cumulative contaminant effects, and evaluate interference with equipment or products. By contrast, a household typically focuses on aesthetic and health concerns and may prioritize point-of-entry treatment options to address detected levels.

How Does the Autotrol 1,2,3-TCP Filter Work to Address This Constituent?

The Autotrol 1,2,3-TCP Filter is designed to treat water containing trace amounts of chlorinated solvents such as 1,2,3-trichloropropane. Using proprietary media and a patented configuration, it adsorbs and neutralizes 1,2,3-TCP molecules, reducing their concentration in water supplied to the household. This system ships ready to configure for integration with existing water setups, and it directly targets the chlorinated solvent without requiring chemical additives or salt-based regeneration methods.

What Should a Household in Pennington County Not Conclude from Regional 1,2,3-TCP Data?

It is important not to assume that the absence of detected 1,2,3-trichloropropane in municipal sampling means all water at every faucet is free from this constituent, nor that any detection in a private well would indicate a violation or unsafe condition. Regional data are based on aggregate measurements for the public system and not on individual household water. The EPA has not set federal maximum contaminant levels (MCLs) for 1,2,3-TCP, so detected presence alone does not imply regulatory noncompliance or health risk. Testing specific water at the tap, followed by consideration of treatment options such as the Autotrol system, is the proper course for households weighing technical approaches.

Where this information comes from

Source: EPA SDWIS public water system record. Sampled 2014-04-15. These figures describe the public water system's record, not the plumbing inside any individual building.

On record: EPA UCMR3 monitoring (2013-2015) for Rapid City (SD4600406), SD: 24 results across 1 listed contaminants, 0 detections above the reporting level; nothing detected above the method reporting level