The East Cherry Creek Valley Water and Sanitation District provides surface water to over 66,000 people in Arapahoe County through nearly 19,300 connections. This community water system is regularly monitored under federal guidelines to ensure water quality meets health standards before reaching taps.
How are reverse osmosis rejection rates stated and why is a percentage not a guarantee?
Reverse osmosis (RO) systems often advertise rejection rates for contaminants, including 1,4-dioxane, as percentages representing the portion removed from water passing through the membrane. However, these numbers do not guarantee exact performance for every water source or household. Variations in water chemistry, pressure, and system design affect actual results. A stated rejection percentage simply reflects performance under controlled test conditions and should be understood as an estimate rather than a definitive measurement for any specific application.
Why does 1,4-dioxane move ahead of the solvent plume it stabilized, and what does that mean downgradient?
1,4-Dioxane is a cyclic ether used as a solvent stabilizer and is known for its high mobility in water. Unlike many contaminants that tend to travel with or behind the solvent plume they accompany, dioxane often moves ahead because it does not bind well to soil or organic matter. This means that in groundwater or surface water, dioxane can spread farther and faster, potentially appearing at points beyond where other solvents or pollutants are detected. For households relying on local water supplies in Arapahoe County, this behavior means dioxane could be present even when other solvents are not detected, emphasizing the need for targeted testing and treatment consideration.
What questions does a commercial or industrial operator add that a household does not?
Commercial and industrial water users often face different regulatory and operational concerns compared to residential households. They may need to consider larger treatment capacities, continuous monitoring, compliance reporting, and the impact of discharge regulations. Households, however, focus on daily water use volume, effective contaminant reduction for safety and aesthetics, and ease of maintenance. For the average home in Arapahoe County, understanding the scale of contaminant concentrations and selecting equipment that matches typical household consumption rates is usually sufficient.
What does the measured range found in Arapahoe County water mean against the relevant federal standard, and what does it not mean?
Federal monitoring from 2013 to 2015 reported one detection of 1,4-dioxane in the East Cherry Creek Valley public water system at 0.072 micrograms per liter (µg/L), equivalent to 0.072 parts per billion (ppb). The EPA has not established a Maximum Contaminant Level (MCL) for this chemical. The EPA’s cancer risk reference concentration is set at 0.35 µg/L, higher than the detected concentration. Importantly, detection in this context indicates the presence measured above the reporting level but is not a violation or a health-based exceedance. This data provides context for what might be in public water but does not reflect individual household water quality, which must be tested separately to determine specific contaminant levels.
How does 1,4-dioxane enter groundwater or the distribution system in this region?
Sources of 1,4-dioxane in water supplies include its use in industrial degreasing, presence in consumer products, and migration from landfill leachate. In Arapahoe County, surface water and groundwater may be influenced by these sources, with dioxane’s chemical properties allowing it to persist and travel through aquifers and into public water systems. Its ability to move ahead of solvent plumes can lead to detection in water treatment plants relying on surface water intakes and groundwater wells.
For households evaluating treatment equipment options for this contaminant, the Fleck 1,4-Dioxane Filter offers a documented approach designed to address the presence of cyclic ethers like 1,4-dioxane at concentrations relevant to typical residential use. This treatment technology ships ready to configure and can be selected based on the household’s measured demand and water test results for targeted control of this solvent stabilizer.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2014-11-10. 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: 22 results across 1 listed contaminants, 1 detections above the reporting level; no federal MCL; EPA cancer risk reference concentration 0.35 ug/L
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