1. Seasonal Water-Table Fluctuations and Solvent Plume Movement Near Well Screens
Fairfax County's water supply depends largely on surface water managed through the Fairfax County Water Authority. Groundwater movement beneath homes in this region undergoes seasonal variations in the water table level. These changes can cause volatile organic compound (VOC) solvent plumes—areas where VOCs are present in water—to shift relative to a home's well screen or water intake point. As the water table rises or falls, different sections of the solvent plume may come into contact with the well screen, influencing VOC levels in the extracted water over time.
2. What "Not Detected" Means in Laboratory VOC Testing
When a laboratory reports a VOC compound as "not detected," it indicates that the measured concentration of that compound was below the laboratory's method detection limit. This limit is the smallest concentration reliably measurable and reportable by the testing procedure. For example, monitoring of Fairfax County's public water system showed no detections of 1,1-dichloroethane above 0.03 micrograms per liter (µg/L), chloromethane above 0.2 µg/L, or other VOCs at their respective detection thresholds. However, "not detected" does not mean the compound is absent; it means the concentration is too low to be confidently measured by that method.
3. How the Pentair VOCs & Industrial Chemicals Filter Removes VOCs
The Pentair VOCs & Industrial Chemicals Filter uses advanced filtration technology designed specifically to address volatile organic compounds in residential water supplies. Its granular activated carbon component adsorbs solvent compounds such as MTBE, chloromethane, and halon 1011, effectively reducing their presence in the treated water. This treatment is capable of handling fluctuations in VOC concentration, providing a consistent barrier against these compounds despite seasonal changes or variations in source water quality.
4. Sources of VOCs in Fairfax County Groundwater and Distribution Systems
In Fairfax County, VOCs can enter groundwater or the public distribution system through various routes including surface water contamination, industrial emissions, and urban runoff. These solvent compounds are typically volatile and may originate from chemical solvents, gasoline additives, or industrial chemical releases that interact with surface waters feeding into the county’s water supply. Because the public water system uses surface water sources, monitoring data reflects area-wide water quality rather than conditions at any individual tap.
5. Differences Between Public Water System Records and Private Well Testing
Data from the Fairfax County Water Authority covers the entire distribution system, serving over 1.1 million people. These records show no health-based violations for VOCs as indicated by EPA compliance data. However, private wells can have different VOC concentrations based on localized factors such as proximity to contamination sources or well depth. Individual household water testing is necessary to determine the exact VOC levels present in private well water, as public system results do not represent specific home conditions.
6. Fixtures and Appliances Most Affected by VOCs in Household Water
Within a household, VOCs first impact fixtures and appliances that use untreated water directly from the supply line. These may include kitchen faucets, ice makers, and water dispensers where VOCs can affect taste and odor. Appliances that heat water, such as coffee makers and dishwashers, may also be impacted due to VOC volatility increasing with temperature. Addressing VOCs at the point of entry protects these fixtures and improves overall water quality for drinking and cooking.
The Fairfax County Water Authority's monitoring data, collected under EPA's Unregulated Contaminant Monitoring Rule from 2013 to 2015, shows no VOC detections above laboratory reporting limits in their public water system. This record reflects system-wide sampling and does not describe conditions in any individual household's water. For personalized information, homeowners should test their own water directly. The Pentair VOCs & Industrial Chemicals Filter ships ready to configure as a tailored solution for households seeking to reduce VOCs and related solvent compounds in their drinking water.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2014-04-14. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for Fairfax County Water Authority (VA6059501), VA: 128 results across 7 listed contaminants, 0 detections above the reporting level; nothing detected above the method reporting level