Distinguishing Gasoline and Dry-Cleaning VOC Residues in Groundwater
Different solvent compounds appear depending on contamination sources
Volatile organic compounds (VOCs), also called volatile organics or solvent compounds, vary in type depending on the source of groundwater contamination. A gasoline release typically introduces hydrocarbons such as benzene, toluene, ethylbenzene, and xylene. In contrast, solvents from dry-cleaning operations include chlorinated compounds like 1,1-dichloroethane and HCFC-22, which are detectable in water samples from the South Bend Waterworks system serving St. Joseph County.
Movement of Solvent Plumes with Seasonal Water-Table Changes
Variations in groundwater levels affect the exposure of well intake screens to VOCs
Seasonal fluctuations in the water table can cause shifts in the position of solvent plumes underground, altering which contaminants may contact well screens at different times of the year. This dynamic means VOC concentrations in water can change over time, even within the same public water system. Understanding this helps explain the intermittent detection of compounds like 1,1-dichloroethane at median levels of approximately 0.62 µg/L (0.62 ppb) in system records from South Bend.
Why Aesthetic Secondary Standards Differ from Health-Based Limits
Detected VOC levels do not equate to health violations
The EPA records for South Bend Waterworks show no health-based violations related to VOCs, despite detections of compounds such as 1,1-dichloroethane and HCFC-22. These detections are measurements above laboratory reporting levels rather than violations. In addition, no federal maximum contaminant levels (MCLs) exist for these specific VOCs under the Unregulated Contaminant Monitoring Rule, so aesthetic secondary standards, which address taste, staining, and corrosion, are not health safety limits.
Household Symptoms That May or May Not Indicate VOCs Presence
Observable signs provide limited insight without specific testing
Symptoms like unusual taste or odor in water can sometimes suggest VOCs, but they are not definitive indicators. Because VOCs are volatile, exposure routes beyond drinking water, including inhalation during showering or cooking, are relevant. However, these symptoms are nonspecific and could result from other water quality factors. To confirm VOC presence at a household level, water testing targeting volatile organics, including the compounds detected in the South Bend system, is necessary.
Granular Activated Carbon Beds and the Importance of Contact Time
Effective VOC removal depends on filter bed size relative to water flow
Filters designed to remove VOCs and industrial chemicals rely on granular activated carbon technology. The performance of such systems depends more on contact time—the duration water spends in contact with the carbon bed—than on flow rate alone. Properly sized carbon beds allow sufficient absorption of solvent compounds like those reported in the South Bend water data. This ensures better reduction of VOCs before water reaches household taps.
Next Step: Ordering a Comprehensive VOC Test for Household Water
Because public water system records represent area-wide data, they cannot specify your home's exact VOC levels. To clarify whether your household water contains VOCs at levels requiring treatment, request a full VOC analysis from a certified laboratory, focusing on the compounds detected in South Bend's supply such as 1,1-dichloroethane and HCFC-22. If VOCs are present, a Fleck VOCs & Industrial Chemicals Filter ships ready to configure for effective reduction, using granular activated carbon technology optimized for your water flow conditions.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2014-04-02. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for South Bend Waterworks (IN5271014), IN: 124 results across 7 listed contaminants, 5 detections above the reporting level; no federal MCL for these UCMR-listed VOCs