The public water system serving Cary, IL, draws from groundwater and has undergone volatile organic compound (VOC) monitoring under the EPA’s Unregulated Contaminant Monitoring Rule (UCMR3) from 2013 to 2015. This system, with 6,469 connections serving over 17,800 residents, shows detections of some VOCs but no exceedances of federal maximum contaminant levels (MCLs) or health-based violations related to VOCs during that period.
How does a gasoline release in groundwater differ from a dry-cleaning release in terms of VOCs?
Gasoline releases typically involve a complex mixture of hydrocarbons, including benzene and toluene, which are highly volatile and tend to produce a plume of solvent compounds that may migrate differently through groundwater compared to dry-cleaning solvents, which often contain chlorinated compounds like perchloroethylene (PCE). In Cary’s groundwater, the detected VOCs include chloromethane and HCFC-22—chlorinated compounds relevant to industrial and refrigerant sources rather than direct gasoline contamination. Understanding these differences helps clarify which solvent compounds might be present based on regional industrial activity.
Why is the size of a granular activated carbon (GAC) bed based on contact time rather than flow rate alone?
Effective removal of VOCs and similar volatile organics depends on the contaminant molecules’ interaction time with the GAC media. A carbon bed sized only by flow rate could pass water too quickly, reducing treatment efficiency. Longer contact time allows for greater adsorption of VOCs such as chloromethane or HCFC-22 detected in Cary’s water system, which supports better performance in removing these compounds from household water supplies, especially when existing equipment is challenged by demand or concentration fluctuations.
What does it mean when a laboratory reports 'not detected' for a compound?
'Not detected' reflects that the laboratory’s method detection limit (MDL)—the lowest concentration measurable with confidence—was not exceeded in the tested sample. For instance, Cary’s system results show no detections above 0.03 µg/L for 1,1-dichloroethane and no bromomethane detections above 0.2 µg/L. This means concentrations, if present, were below the capability of current laboratory methods to reliably quantify, rather than confirming absolute absence.
How do plumbing material and age influence VOC levels compared to source water?
While VOCs primarily originate from source water contamination, plumbing materials and system age can affect the water’s contact and retention time within household pipes, potentially influencing the presence or transformation of volatile organics. Older plumbing may harbor residues or promote off-gassing in rare cases, so evaluating plumbing conditions can be part of diagnosing persistent VOC detection or treatment challenges beyond addressing the source water itself.
What is the recommended sequence of checks and tests to address VOC concerns in household water?
Start with a cost-effective visual and operational check of household water equipment, followed by basic water quality parameters such as taste and odor changes linked to VOCs. Next, consider water sampling at your tap with an approved laboratory test targeting volatile organic compounds to measure specific solvent compounds mentioned in the EPA’s monitoring results for Cary. This targeted test is the definitive step that clarifies your household’s VOC profile.
When existing treatment equipment struggles with VOCs, technologies like the Autotrol VOCs & Industrial Chemicals Filter can be directly purchased and shipped ready to configure, providing an effective barrier against solvent compounds through granular activated carbon filtration designed for robust contact time and adsorption capacity.
Ultimately, the specific laboratory test measuring VOCs concentration in your household tap water offers the clearest indication of treatment needs and effectiveness, settling uncertainties generated by system-wide monitoring data and enabling informed water quality management decisions.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2013-11-22. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for Cary (IL1110100), IL: 108 results across 7 listed contaminants, 5 detections above the reporting level; no federal MCL for these UCMR-listed VOCs
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