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1. Is my drinking water safe?

Your water continues to be safe to drink and use based on the EPA health advisory level. Water from your tap meets every federal and state standard for safe drinking water. There have been no exceedances of state or federal regulations for 1,4-dioxane or any other drinking water contaminant. Levels of 1,4-dioxane detected in District wells and drinking water reservoirs are consistently below the EPA health advisory level. A health advisory is a guideline that represents an estimated acceptable level for a substance in drinking water based on health effects information. For more information, see the Agency for Toxic Substance & Disease Registry website https://www.atsdr.cdc.gov/substances/toxcommunity.asp

2. Is this substance in my water?

The testing that the District has conducted for the presence of 1,4-dioxane has confirmed that this substance is present in some of the District’s groundwater supplies. Tests on treated drinking water confirm the presence of this substance at an average concentration of 1.3 parts per billion in District water supplies in 2016.

3. What is a part per billion?

Substances found at very low levels in water are often measured at the level of parts per billion (ppb). A part per billion is the same as one microgram per liter (ug/L). One part per billion is equivalent to one second in 32 years or a single penny in ten million dollars.

4. How did the District find out that 1,4-dioxane was in the District’s groundwater sources?

In 2011, the EPA identified 1,4-dioxane as an emerging substance of concern as part of a periodic Superfund review. In response to the review, the District began testing for the presence of 1,4-dioxane in groundwater supplies. This is an unregulated substance, meaning there is no drinking water standard for this substance. The District’s water quality chemists conducted sampling to determine if this compound was present. Samples were collected and sent to an independent, certified laboratory. Test reports confirmed that 1,4-dioxane was detected in some samples. The District shared results with the Colorado Department of Public Health and Environment and Tri-County Health Department. Since the presence of 1,4-dioxane was found, the District completed additional sampling using EPA-approved methods.

5. What is 1,4-dioxane?

1,4-Dioxane is a man-made compound. It was primarily used as an industrial solvent or solvent stabilizer in the 1970’s and 1980’s and widespread use has reduced. Today, 1,4-dioxane is used mostly as a solvent in paints, varnishes, resins, lacquers, and can be found in some cosmetics, deodorants, toothpaste and soaps. 1,4-Dioxane has been classified by the EPA as likely to be carcinogenic to humans at certain levels.

6. What level of 1,4-dioxane is considered safe in drinking water?

The EPA has established safe levels for over one hundred substances that may be in public drinking water sources. There is no EPA or State of Colorado drinking water standard for 1,4-dioxane. The EPA has set a health advisory level of 35 parts per billion for 1,4-dioxane. The average concentration in the District’s drinking water is 1.3 parts per billion which is well below this EPA health advisory level. EPA health advisories are informal guidance levels for unregulated substances in drinking water, issued by the federal government to help states, local health officials, and community water systems in protecting public health. 

7. What is the District doing now that it knows this substance is present in the water?

The District’s primary goals are to inform the public that this substance has been detected in some of the District’s source waters and to continue to work with State and Federal agencies to address the source. To that end, we have been meeting with the State and EPA to share information and coordinate sampling efforts.

The District has taken many proactive steps in response to the detection of 1,4-dioxane in its water supply.
• In 2013, the District expanded the water laboratory at the Klein Water
Treatment Facility to be able to accurately analyze for this substance.
• The District continues to monitor 1,4-dioxane concentrations in its water
supply
• The District has blended its water sources to minimize concentrations to the
extent practical and assure that concentrations are well below the EPA health
advisory.
• The District has also engaged water treatment and engineering consultants to
help us examine ways to minimize the presence of this substance. This includes
pilot study testing of a process to remove the substance as well as cost
estimates for construction of treatment capacity.

8. Does the District know the source of 1,4-dioxane?

The District has identified the main source of the substance as the Chemical Sales Co. Superfund site near 46th and Monaco St. in Denver, CO. Information we have gathered has been shared with the State and EPA who oversee remediation of the site. We are working alongside these agencies to perform additional groundwater sampling and testing. This work will further the efforts to better locate the origin of the contamination and inform future cleanup decisions related to this substance.

9. How are the State and EPA working to address the source of 1,4-Dioxane in the District's drinking water supply?

The Chemical Sales Co. Superfund site is the apparent source of much of the 1,4-Dioxane loading to groundwater. Remediation of this site, located near 46th and Monaco in Denver, is managed by the CDPHE with oversight from the EPA. The District continues to work with these agencies regarding source control of the substance. More information on EPA's and CDPHE's activities can be found at the following websites: https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0800866,  https://www.colorado.gov/pacific/cdphe/chemical-sales-company. More detailed information on the cleanup can also be found at  https://semspub.epa.gov/work/08/100001630.pdf. 

10. How will the District keep customers informed about the occurrences of 1,4-Dioxane?

The District has a page on its website to keep the public aware of current District activities related to this substance. Links will also be provided on the District’s website regarding information published by the EPA and State as well as other related technical resources.
The District has previously and may continue to provide information from time to time by mail to District customers for those preferring to have information in a hard-copy format.

11. How can I contact the District to get more information on this topic?

If you would like a copy of the District’s current Water Quality Report, you can read and download the report from a link on the District’s website home page or by direct link at www.sacwsd.org/WQR. For additional information, please contact the District’s Water Quality Information Line: Phone: 303.287.6454; Email: wqinfo@sacwsd.org; Website: www.sacwsd.org