Understanding 1,2,3-TCP in Tulare County Water: Key Data and Treatment Options for Households

The public water system serving Tulare County, specifically CA Water Service - Visalia, draws from groundwater sources and provides water to nearly 150,000 residents across more than 47,000 connections. According to the EPA's UCMR3 monitoring conducted between 2013 and 2016, 1,2,3-trichloropropane (1,2,3-TCP) was detected in some samples from this system, with measured concentrations ranging from non-detect to a highest detected value of 0.052 micrograms per liter (µg/L), equivalent to parts per billion (ppb). Importantly, no health-based violations are on record for this water system from EPA assessments.

Why the Reporting Level for This Chlorinated Solvent Is Set Thousands of Times Lower Than That for Common Metals

The laboratory reporting level for 1,2,3-TCP is 0.03 µg/L, a threshold established due to the compound's potential health concerns even at very low concentrations. This value is significantly lower than detection limits for many common metals found in water because 1,2,3-trichloropropane is a synthetic chlorinated solvent whose presence is strictly monitored despite no federal maximum contaminant level (MCL) having been set. The sensitivity of testing methods means that detections of TCP at parts per trillion or low parts per billion levels are possible, enabling early awareness of even slight concentrations in groundwater sources.

How a Soil Fumigant Impurity From the Mid-20th Century Reached Groundwater Decades Later

1,2,3-TCP originated as an impurity in soil fumigant products widely used in agriculture in the 1950s through the 1980s. Its chemical stability and mobility allowed it to persist and infiltrate deep groundwater layers over subsequent decades. The agricultural history of Tulare County, known for intensive farming, aligns with the presence of 1,2,3-TCP detections in system groundwater. This extended timeline from surface application to groundwater detection illustrates both the compound’s resilience and the long-term legacy it can leave in water supplies.

Interpreting 'Detected', 'Median', and 'Range' in the System's 1,2,3-TCP Sampling Record

• Detected: Means the chemical was measured above the reporting threshold (0.03 µg/L) in a subset of samples during the federal occurrence study, not that any regulatory limit was exceeded.
• Median of Detections: At 0.043 µg/L, this value represents the middle concentration value among all detected samples, offering a central tendency but not an absolute level for any individual home.
• Range: The highest detected concentration was 0.052 µg/L, with many samples below detection, demonstrating variability across locations and times within the water system.

These statistics help households understand the typical and maximum levels found in the system's groundwater but do not replace testing of an individual home’s tap water to know exact local conditions.

California’s 5 Nanogram per Liter Limit Compared With Federal Absence of a Maximum Level

In contrast to federal regulations, California enforces a stringent public health goal for TCP in drinking water of 0.005 µg/L, or 5 nanograms per liter (ng/L), to guide management and treatment. This state limit is lower than the federal reporting level and reflects precautionary objectives. The system sampling results, while not directly comparable as they are historical and system-wide, indicate that some detections exceeded this California guideline. Residents concerned with this standard may consider treatment options accordingly.

Agricultural Land Use in Tulare and Its Connection to TCP Detections

Tulare County’s extensive agricultural activity, especially historically intensive crop production, has been linked to the presence of 1,2,3-TCP in groundwater. The use of fumigants containing the compound as an impurity decades ago has left a legacy detected in well-based water supplies. Understanding this connection helps households recognize the potential source rather than assuming current contamination. Local well water testing provides clarity for specific residences.

Maintenance Rhythm of the C-Series Equipment for TCP Treatment

The C-Series 1,2,3-TCP Filter ships ready to configure for residential use and is designed to address the chlorinated solvent to levels suitable for household demand. Maintenance generally involves periodic media replacement as outlined in the product manual, ensuring effective performance over time. The rhythm and specifics depend on household water usage, water quality variation, and local TCP levels. This approach provides manageable upkeep without requiring professional services and helps maintain treated water quality.

In summary, the EPA’s system-level measurements for CA Water Service - Visalia in Tulare County provide valuable insight into the occurrence of 1,2,3-trichloropropane in groundwater, revealing measured levels well below federal health-based violation thresholds. Awareness of reporting thresholds, state guidelines, agricultural history, and treatment maintenance is essential for households evaluating water treatment equipment like the C-Series 1,2,3-TCP Filter. Testing of your own water supply is recommended to confirm your household’s specific conditions. The EPA’s public water system records offer ongoing transparency for this region’s water quality.

Where this information comes from

Source: EPA SDWIS public water system record. Sampled 2016-01-12. These figures describe the public water system's record, not the plumbing inside any individual building.

On record: EPA UCMR3 monitoring (2013-2015) for CA Water Service - Visalia (CA5410016), CA: 86 results across 1 listed contaminants, 6 detections above the reporting level; no federal MCL