You may notice a metallic taste or simply be concerned about what’s in your water after hearing about chromium-6 in Kitsap County. According to federal monitoring data, the Silverdale Water District supplies water sourced from groundwater to over 35,000 residents through more than 10,000 connections. From December 2014 to June 2015, chromium-6 (also known as hexavalent chromium or Cr(VI)) was detected in this system, with measurements ranging up to 9.9 micrograms per liter (µg/L), or parts per billion (ppb).
Why Can’t Total Chromium Levels Explain Chromium-6 Concerns?
Government testing reports both total chromium and chromium-6 separately. Total chromium includes multiple forms of chromium, predominantly trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)). While Cr(III) is generally less reactive and less mobile, Cr(VI) is a specific form that has drawn attention due to its chemical behavior. The total chromium measured in Silverdale Water District’s records reached up to 10.0 µg/L, but this figure alone doesn’t reveal how much chromium-6 is present. Understanding chromium-6 specifically requires separate measurement because total chromium does not indicate the oxidation state or toxicity differences between the chromium species.
How Does Chromium’s Oxidation State Change From Source To Tap?
Chromium-6 originates in groundwater in the Kitsap area, but it can shift chemically as water moves through distribution pipes and household plumbing. Changes in factors like pH, organic matter, and pipe material can reduce chromium-6 to trivalent chromium or transform it otherwise. This means chromium-6 levels at your tap can differ from the levels found at the well or treatment plant. None of these changes suggest unsafe water; they simply reflect typical chemical processes occurring naturally over time and distance.
What Should You Note Before Seeking Treatment Advice?
Before pursuing any water treatment options, record details such as:
- The source of your water: is it from Silverdale Water District or a private well?
- Any recent water quality tests you have done, especially for chromium-6 or total chromium.
- Specific observations like taste, color, or staining, though these do not establish chromium-6 presence.
- Your water usage habits and any filtration or softening devices currently in use.
These factors help clarify what treatment methods may be suitable and necessary.
What Do 'Detected', 'Median', and 'Range' Mean in the Sampling Record?
Federal monitoring classifies a chromium-6 measurement as 'detected' if it is above the reporting level of 0.03 µg/L. In the Silverdale Water District’s 44 results, 38 showed detections, indicating that instruments measured chromium-6, not that levels were unsafe. The 'median of detections' (5.8 µg/L) is the middle value among those detected samples, providing a sense of typical concentration, while the 'highest' value (9.9 µg/L) indicates the maximum detected during that period. These figures are strictly observational and not regulatory limits or findings of contamination.
How Do Public Water System Records Differ From Private Well Testing?
Records for systems like Silverdale Water District represent aggregated water quality data at the system level, serving many households. They do not reflect individual well conditions or plumbing variations within homes. Private wells can have different chromium-6 levels or other constituents due to local geology and well construction. To know your water’s specific chromium-6 content, a targeted lab test on your own tap or well water sample is necessary.
For homeowners in Kitsap County concerned about chromium-6 in their water, the key step is to arrange for an individual water test that quantifies chromium-6 concentration directly from your tap. A clear result from a certified laboratory will provide the definitive information needed to decide on any treatment. When treatment is considered, the Autotrol Chromium-6 Filter ships ready to configure as a documented solution designed to address chromium-6 effectively in household water.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2015-06-29. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for Silverdale Water District #16 (WA5379300), WA: 88 results across 2 listed contaminants, 78 detections above the reporting level; no federal MCL for hexavalent chromium; total chromium MCL 100 ug/L