What the UCMR3 Nationwide Survey Was Designed to Learn, and Its Limits for One Household
The Unregulated Contaminant Monitoring Rule 3 (UCMR3) survey conducted by the EPA sampled public water systems—including the City of Chandler’s system serving Maricopa County between 2013 and 2015—to gather occurrence data on chromium-6 (hexavalent chromium or chromium(VI)). This extensive survey was not intended to establish compliance or health safety for individual home supplies. Instead, it provides a regional snapshot of chromium-6 presence in public surface water sources as measured in 71 samples, with 68 detecting chromium-6 above 0.03 micrograms per liter (µg/L). For any single household, only testing of the actual water at the tap can clarify its chromium-6 concentration and treatment needs.
What Questions a Commercial or Industrial Operator Adds That a Household Does Not
Unlike residential users, commercial or industrial water users often require detailed operational parameters such as flow rates, peak loads, and specific regulatory compliance thresholds that guide their treatment decisions. Households, by contrast, focus primarily on consistent water quality appropriate for everyday use amid moderate daily water consumption. Therefore, a household’s evaluation centers on how well existing treatment equipment keeps up with chromium-6 levels typical for Chandler’s public supply and whether enhanced filtration can sustain safe and aesthetically acceptable water.
How Many Samples and Wells Stand Behind the Figures, and What a Small Sample Means
The City of Chandler’s chromium-6 data is based on 71 samples from their public water system, which serves 247,328 people through over 81,000 connections. These samples were primarily from surface water sources, providing a broad but generalized picture. The median chromium-6 concentration detected was 3.95 µg/L, with a highest measured level of 19.0 µg/L. Because this is a regional occurrence dataset rather than a precise measurement per household, individual wells or tap water may differ widely. Households should obtain laboratory testing specific to their water to understand true chromium-6 levels.
What the Measured Range Means Against the Relevant Federal Standard, and What It Does Not Mean
Chromium-6 does not currently have a federal Maximum Contaminant Level (MCL) under the Safe Drinking Water Act. However, total chromium, which includes all forms of chromium, has an MCL of 100 parts per billion (µg/L). The City of Chandler’s measured highest chromium concentration was 23.0 µg/L, well below the total chromium MCL. Detection of chromium-6 or total chromium in water at these levels is neither a violation nor an indication of water being unsafe under federal standards. The measurements should be viewed as data points to inform decisions rather than alarms demanding immediate action.
How the Treated Water Differs at the Tap Once the Documented Technology Is in Place
To support households where existing treatment equipment is strained by chromium-6 presence, using dedicated filtration technology designed for chromium(VI) offers consistent performance. The Fleck Chromium-6 Filter ships ready to configure, integrating advanced filtration methods that specifically target hexavalent chromium and reduce its concentration in water delivered to taps. This technology complements existing equipment, helping maintain water quality levels aligned with household expectations for taste, clarity, and safety.
Why California Set Its Own 10 µg/L Limit and What That History Means for a Reader Elsewhere
California established a public health goal of 10 µg/L for chromium-6 based on epidemiological studies linking chromium(VI) to potential health risks. This standard is unique to California and not federally mandated. In Maricopa County, detections frequently fall below or near this guideline, but no direct regulatory requirement exists to meet it. For households in Chandler, this means contextualizing regional data with personal water tests and treatment choices rather than applying California’s limit as a strict benchmark.
In summary, understanding chromium-6 data for Chandler involves recognizing that regional sample results guide but do not dictate individual household water quality. Testing at the tap is essential for accurate assessment, and when existing equipment shows limits in handling chromium(VI), a dedicated solution like the Fleck Chromium-6 Filter can provide targeted support to maintain drinking water quality.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2014-11-18. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for City of Chandler (AZ0407090), AZ: 142 results across 2 listed contaminants, 134 detections above the reporting level; no federal MCL for hexavalent chromium; total chromium MCL 100 ug/L
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