Metropolitan Water Board

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1. Is my municipal water safe? Your water remains safe according to current EPA health advisory levels. Water from your tap meets all federal and state standards for safe consumption. No exceedances of state or federal regulations have been found for 1,4-dioxane or other water contaminants. Detected levels of 1,4-dioxane in District wells and reservoirs consistently remain below EPA health advisory thresholds. These advisories represent acceptable levels based on comprehensive health data. For additional information, visit the Agency for Toxic Substance & Disease Registry at https://www.atsdr.cdc.gov/materials/toxcommunity.asp
2. Is this substance present in my water? Testing conducted by the District has confirmed the presence of 1,4-dioxane in certain groundwater sources. Analysis of treated municipal water verified this substance at an average concentration of 1.3 parts per billion in District supplies during 2016.
3. What does parts per billion mean? Substances found at very low concentrations are measured in parts per billion (ppb), equivalent to one microgram per liter (ug/L). To visualize this scale: one ppb equals one second in 32 years or a single penny in ten million dollars.
4. How was 1,4-dioxane discovered in the District's water? The EPA identified 1,4-dioxane as an emerging concern during a 2011 Superfund review. In response, the District began testing groundwater supplies for this unregulated substance. Water quality chemists collected samples for analysis by independent, certified laboratories, confirming the presence of 1,4-dioxane. Results were shared with health authorities, and additional testing using EPA-approved methods was implemented.
5. What exactly is 1,4-dioxane? This synthetic compound was primarily used as an industrial solvent or stabilizer during the 1970s-1980s, with usage declining significantly since then. Today, it appears in paints, varnishes, resins, and some personal care products like cosmetics and soaps. The EPA classifies 1,4-dioxane as a probable human carcinogen at certain exposure levels.

The EPA has established safety thresholds for over 100 potential water contaminants, though no specific standard exists for 1,4-dioxane. Currently, the EPA recommends a health advisory level of 35 parts per billion. The District's average concentration is 1.3 ppb, well below this guideline. These advisories provide informal guidance for unregulated substances to help local authorities protect public health.

The District has taken proactive measures upon detecting 1,4-dioxane, including expanding laboratory capabilities, continuous monitoring, strategic water source blending, and consulting with treatment experts. The primary contamination source has been identified as the Chemical Sales Co. Superfund site near 46th and Monaco St. in Denver, with remediation oversight from state and federal agencies.

For further information about cleanup efforts, visit: https://gemgrp.com/eReports/CNMA000137Y18.pdf or https://www.colorado.gov/pacific/cdphe/chemical-sales-company. The District maintains dedicated communication channels for residents seeking information: Phone: 303.287.6454; Email: wqinfo@sacwsd.org; Website: www.sacwsd.org.