Laboratory reports for chromium(VI), often called chromium-6, list measured concentrations in micrograms per litre (µg/L), also known as parts per billion (ppb). For the East Cherry Creek Valley Water and Sanitation District, serving Arapahoe County, EPA's Unregulated Contaminant Monitoring Rule (UCMR3) from 2013-2015 shows 36 chromium-6 samples were taken. Out of these, 14 detected chromium(VI) above the reporting level of 0.03 µg/L, with the highest result recorded at 0.054 µg/L and a median of 0.0385 µg/L for positive detections. These findings reflect the system’s surface water source and provide context for understanding chromium-6 presence locally.
How Ion Exchange and Reverse Osmosis Differ in Addressing Chromium(VI)
When considering treatment for hexavalent chromium, ion exchange technology specifically targets dissolved ions including chromium-6 by exchanging them for less problematic ions, effectively lowering chromium(VI) concentrations in water. This process can be selective and efficient for ionic contaminants.
Reverse osmosis, by contrast, uses a semi-permeable membrane that removes a broad spectrum of dissolved substances including chromium-6 based on particle size and diffusion properties. It is less selective than ion exchange but can reduce total dissolved solids alongside chromium(VI).
Both technologies can be effective, but their mechanisms differ: ion exchange is an adsorption and replacement process focused on ions, while reverse osmosis is a physical barrier filtering dissolved substances.
Trivalent Versus Hexavalent Chromium: Why Total Chromium Results Fall Short
Water quality reports list total chromium to include all chromium species, primarily trivalent chromium (chromium-3) and hexavalent chromium (chromium-6). These forms differ chemically and in their behavior in water and treatment.
Total chromium results do not distinguish the proportion of chromium-6, which is of particular interest. Hexavalent chromium is typically more mobile and treated differently from trivalent chromium. Thus, relying solely on total chromium data cannot provide a clear understanding of chromium-6 levels, making specific chromium-6 testing necessary for informed decisions.
The Role of Plumbing Material and Age, Separate From Source Water
Chromium levels measured in a water system’s source or distribution do not account for potential changes within household plumbing. Older pipes or plumbing materials may contribute additional metals or alter water chemistry, influencing chromium speciation or concentrations at the tap.
Therefore, even if the system’s water shows certain chromium-6 levels, household factors can affect final water quality. It’s advisable to consider plumbing conditions independently of source water data when assessing chromium-6 concerns.
Consequences of Leaving Chromium-6 Untreated Over Time
Persistent presence of chromium(VI) in household water without mitigation does not inherently indicate a safety violation but can warrant attention depending on concentration and duration. Over years, untreated chromium-6 can contribute to corrosion issues and affect water taste or appearance, depending on local water chemistry.
Understanding potential long-term effects requires specific knowledge of chromium-6 levels at the tap and consultation with testing resources to determine if treatment is beneficial.
Comparing Arapahoe County’s Chromium-6 Record With Neighboring Areas
Arapahoe County’s East Cherry Creek Valley system’s chromium-6 detections provide one perspective. Comparing these results with nearby counties helps contextualize local water quality trends but should avoid overinterpretation.
Sampling methods, water sources, and treatment practices vary between systems. Differences in chromium-6 detection frequencies or concentrations may reflect these factors rather than inherent issues. Thus, regional comparisons can guide awareness but cannot confirm specific household conditions.
The Order of Ruling Things Out: From Basic Checks to Laboratory Testing
For households concerned about chromium-6, begin with non-intrusive checks: verify your water source and review the local water system’s published data. Inspect plumbing materials and note any water quality changes that might relate to infrastructure.
Next, consider collecting a water sample for laboratory testing focused on chromium-6 concentration. Testing specifically for chromium(VI) informs tailored responses, distinguishing it from total chromium or other metals.
When considering treatment, technologies like the C-Series Chromium-6 Filter ship ready to configure and use, designed to address hexavalent chromium based on documented principles of ion exchange technology.
Summary: This page walked through understanding laboratory chromium-6 results for Arapahoe County’s water system, contrasted ion exchange and reverse osmosis approaches to chromium(VI), highlighted the difference between hexavalent and total chromium, and explained plumbing's role. It also guided on evaluating long-term impacts, regional data context, and a logical sequence for testing and decision-making.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2014-11-24. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for East Cherry Creek Valley WSD (CO0103035), CO: 72 results across 2 listed contaminants, 24 detections above the reporting level; no federal MCL for hexavalent chromium; total chromium MCL 100 ug/L