Oxidation State Changes from Source to Tap in Lehigh County
Residents in Lehigh County using water supplied by the LCA-WLSA Central Division system receive surface water that undergoes chemical changes as it moves from the source through the distribution system to household taps. Chromium in water primarily exists as chromium-3 or chromium-6, with chromium-6 (hexavalent chromium, Cr(VI)) being more chemically reactive. The oxidation state can shift during treatment and transit, impacting how chromium behaves in water and how it interacts with plumbing and appliances.
Understanding Aesthetic Secondary Standards Versus Health-Based Guidelines for Chromium-6
The Environmental Protection Agency (EPA) sets health-based Maximum Contaminant Levels (MCLs) for total chromium at 100 micrograms per liter (µg/L or parts per billion). However, there is currently no federal MCL established specifically for chromium-6. Secondary standards address aesthetic factors like taste, staining, and corrosivity, which differ from health-related thresholds. For chromium-6 in Lehigh water, detections below levels considered harmful by the EPA are typical, but aesthetic effects such as discoloration or metallic taste can still occur.
Interpreting Certified Laboratory Tests for Chromium-6
A certified lab test for chromium-6 reports the measured concentration in micrograms per liter (µg/L). For Lehigh County’s public water system, all 60 chromium-6 samples in a past federal occurrence study detected chromium-6 above the reporting level of 0.03 µg/L, with values ranging from 0.03 to 0.74 µg/L and a median of 0.385 µg/L. These figures represent system-wide measurements, not an individual household's water level. Testing a home’s water directly is necessary to know precise chromium-6 concentrations within that residence.
Ruling Out Chromium-6 Concerns: A Stepwise Approach
Before approaching chromium-6 treatment, residents should follow a sequence of checks:
- Check for visible or taste changes indicating aesthetic issues possibly linked to chromium-6.
- Review any publicly available water quality reports from local authorities for your system.
- Conduct certified laboratory testing of your home’s water for chromium-6 to determine exact levels.
- Identify any plumbing or fixture issues that might influence water chemistry.
This structured process helps clarify whether chromium-6 concentrations warrant targeted treatment.
Understanding Detected Levels, Median, and Range in Lehigh’s Chromium-6 Sampling
In the EPA’s monitoring data for Lehigh County’s water system, “detected” means measured above an analytical reporting limit, not that chromium-6 levels pose a violation or health risk. The median value of 0.385 µg/L represents the middle concentration among detections during the survey period, while the range (0.03 to 0.74 µg/L) shows variability across sampling locations and times. These data reflect system-wide findings and cannot specify individual household water quality.
Fixtures, Appliances, and Processes First Impacted by Chromium-6
Chromium-6’s chemical form can contribute to metallic taste and may cause staining on fixtures or affect water-using appliances sensitive to water chemistry. Faucets, showerheads, and appliances like coffee makers or humidifiers that frequently contact tap water may be the first points where chromium-6 effects become noticeable. Addressing chromium-6 presence early helps maintain appliance longevity and culinary water quality.
For Lehigh County homeowners measuring chromium-6 levels near or above their aesthetic comfort threshold, the Pentek Chromium-6 Filter ships ready to configure and is documented to target chromium(VI) effectively. This option allows control over chromium-6 concentrations based on actual household water measurements, offering a focused approach to improve water quality where needed.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2014-12-11. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for LCA-WLSA Central Division (PA3390073), PA: 120 results across 2 listed contaminants, 120 detections above the reporting level; no federal MCL for hexavalent chromium; total chromium MCL 100 ug/L
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