Understanding 1,2,3-TCP in Kent County: Water Quality Insights for Dover Households

If you notice unusual taste or staining at your tap, understanding what might be affecting your household water is important. In Dover, Kent County, a constituent called 1,2,3-trichloropropane (also known as 1,2,3-TCP or TCP) has been closely studied in local groundwater, which is the source for the public water system serving over 39,000 people.

How Does Kent County's Agricultural History Relate to 1,2,3-TCP in Groundwater?

Between the mid-20th century and the 1980s, certain soil fumigants containing impurities like 1,2,3-trichloropropane were commonly used in regional agriculture. Over time, these compounds seeped downward and entered deep groundwater layers. This historical use explains why federal monitoring programs have tested for 1,2,3-TCP in public water supplies like Dover’s groundwater system.

What Do California's 5 Nanograms per Liter Guideline and the Lack of a Federal MCL Mean for Dover Water?

The state of California has set a public health goal for 1,2,3-TCP in drinking water at 0.005 micrograms per liter (5 parts per trillion), reflecting concern for potential long-term exposure. However, the Environmental Protection Agency does not currently have a maximum contaminant level (MCL) for 1,2,3-TCP at the federal level. For the Dover Water Department, federal surveys from 2013-2015 detected no 1,2,3-trichloropropane above the reporting level of 0.03 micrograms per liter (30 parts per trillion), which is higher than California's guideline but still below any enforceable federal limit. This absence of an MCL means there is no legal threshold defining unsafe levels federally, although some states may use advisory targets.

How Reliable Are the 1,2,3-TCP Data Based on the Number of Samples and Wells Tested?

The reported figures for Dover’s public water system come from 28 samples taken during the 2013-2015 Unregulated Contaminant Monitoring Rule (UCMR3) survey. While this sampling provides a snapshot of the system’s water quality, it represents a limited dataset relative to the total number of connections serviced. Because 1,2,3-TCP levels can vary locally and over time, individual homes may experience different concentrations. To know precisely what is in your water, direct testing of your household supply is necessary.

Why Does 1,2,3-Trichloropropane Resist Air Stripping and What Are the Implications for Treatment?

1,2,3-TCP is a chlorinated solvent that tends to be resistant to removal by air stripping, a method that transfers volatile contaminants from water to air. This chemical's low volatility means air stripping is inefficient for reducing 1,2,3-trichloropropane concentrations. Therefore, treatment technologies relying on air stripping usually do not address this compound effectively. Selecting a treatment designed specifically for chlorinated solvents is critical for households concerned about 1,2,3-TCP.

How Does Granular Activated Carbon Contact Time Influence Treatment of 1,2,3-TCP Compared to Taste-Related Issues?

Granular activated carbon (GAC) is often used to improve water quality by adsorbing contaminants. The effectiveness of GAC for reducing 1,2,3-TCP depends heavily on contact time—the duration the water remains in contact with the carbon bed. For 1,2,3-trichloropropane, longer contact times and deeper carbon beds are more critical than for treating taste or odor compounds. This is because TCP molecules interact differently with the carbon, requiring sufficient exposure to ensure adsorption. Systems designed with appropriate bed depth and flow rates can provide households greater confidence in addressing 1,2,3-TCP concerns.

What Should Dover Residents Not Assume Based on Regional 1,2,3-TCP Data?

While federal monitoring in Dover’s groundwater system shows no detection of 1,2,3-TCP above the reporting limit and no federal health-based violations related to this compound, these results reflect the public water supply on average, not the water at any particular faucet. The absence of detection in monitored samples does not guarantee that every household’s water is free from 1,2,3-trichloropropane. To be certain, homeowners should consider testing their own water supply. For those seeking a documented solution, the Pentair 1,2,3-TCP Filter ships ready to configure and utilizes technology proven to reduce chlorinated solvents like TCP from residential water sources.

Where this information comes from

Source: EPA SDWIS public water system record. Sampled 2015-03-12. These figures describe the public water system's record, not the plumbing inside any individual building.

On record: EPA UCMR3 monitoring (2013-2015) for Dover Water Department (DE0000571), DE: 28 results across 1 listed contaminants, 0 detections above the reporting level; nothing detected above the method reporting level