The table below summarizes Thornton's drinking water's most recent PFAS sampling results. 

ND - Not Detected

~ approximate value, result is below the lab reporting limit

* Hazard Index evaluates the concentrations of PFBS, PFNA, PFHxS, and GenX as a group

The table below summarizes Thornton’s PFAS sampling results. Thornton is actively reducing PFAS concentrations in our customer’s drinking water. However, we expect variability in these results due to differences between Thornton’s various raw water sources, seasonal variability within each raw water source, and variability of water treatment plant performance. Thornton has optimized the existing treatment processes where possible, but water quality coming into the treatment plant can vary and may affect how much the treatment system removes PFAS.

ND - Not Detected

~ approximate value, result is below the lab reporting limit

* Hazard Index evaluates PFBS, PFNA, PFHxS, and GenX as a group

There is no immediate public health risk; people need not stop drinking their water now. Water systems are taking steps to lower the levels of PFAS in light of the draft NPDWR from the EPA. The state health department will keep providing facts to help inform the public about the latest science. Notably, the draft MCLs have not yet become regulated, and utilities are not required to meet those limits. However, Thornton believes in protecting public health, and the Water Treatment and Quality group is performing temporary measures to reduce PFAS levels to meet the draft MCL while pursuing more permanent solutions. 

Per- and poly-fluoroalkyl substances (PFAS) are a group of manufactured chemicals that have been used in industry and consumer products since the 1940s. PFAS have characteristics that make them useful in various products, including nonstick cookware, waterproof clothing, stain-resistant carpets and fabrics, firefighting foam, and certain manufacturing processes. There are thousands of different PFAS. The domestic production or use of some PFAS (like PFOA and PFOS) has been largely phased out, but others continue to be used. 

PFAS tend to break down extremely slowly in the environment and can build up in people, animals, and the environment over time. PFAS have been found in water, air, and soil across the nation and around the globe. Because of this, PFAS can end up in the water sources communities rely on for drinking water. Scientific studies show links between certain levels of PFAS exposure and harmful health effects in humans and animals.

On March 14th, 2023, the US EPA released the National Primary Drinking Water Regulation (NPDWR) draft for PFAS. There will be a 60-day public comment period. The EPA considers all public comments informing the final regulation's development. The EPA expects to finalize the PFAS NPDWR by the end of 2023 or early in the first quarter 2024. Once completed, drinking water utilities like Thornton must meet the regulations within three years. 

In the proposed rule, EPA proposes a Maximum Contaminant Level Goal (MCLG) and a Maximum Contaminant Level (MCL) for these six PFAS. MCLGs are non-enforceable public health goals. An MCLG is the level of a contaminant in drinking water at which no known or anticipated adverse health effects occur and which allows an adequate margin of safety. MCLGs consider only public health risks for sensitive populations like pregnant people, developing babies and infants, children, the elderly, and immunocompromised individuals. MCLGs do not consider limits of detection or treatment technology effectiveness. Therefore, MCLGs are sometimes set at levels water systems cannot meet because of current technological limitations. For example, if a contaminant is a known or likely carcinogen, EPA sets the MCLG at 0. MCLs are enforceable standards. An MCL protects public health by setting a maximum level of contaminant allowed in drinking water, which can be delivered to public water system users. The EPA must establish an enforceable MCL as close to the MCLG as is feasible. The EPA evaluates feasibility according to several factors, including costs and benefits, the ability to measure the regulated chemicals in drinking water, and whether proven treatment technologies capable of removing these chemicals under laboratory and field conditions exist. 

EPA proposes to regulate four PFAS – PFHxS, GenX Chemicals, PFNA, and PFBS – as a mixture, using an established approach called a hazard index. The Hazard Index is a tool used to evaluate health risks from simultaneous exposure to mixtures of certain chemicals. Many PFAS are found together and in different levels and combinations. Estimating risk by considering one chemical at a time may underestimate the health risks associated with exposure to many PFAS simultaneously. 

To prevent health risks from mixtures of certain PFAS in drinking water, EPA proposes using this Hazard Index calculation to regulate PFHxS, GenX Chemicals, PFNA, and PFBS in public water systems. To determine the Hazard Index for these four PFAS, water systems would monitor and compare the amount of each PFAS in drinking water to its associated Health-Based Water Concentration (HBWC), which is the level below which no health effects are expected for that PFAS. Water systems would add the comparison values for each PFAS contained within the mixture. If the value exceeds 1.0, it will exceed the proposed Hazard Index MCL for PFHxS, GenX Chemicals, PFNA, and PFBS.

Scientists are studying the health effects of elevated PFAS blood levels. Preliminary research indicates that health effects may include certain types of cancer, high cholesterol, and decreased vaccine response in children. Because of their prevalence in our homes from products we purchase, as well as environmental exposure via the air, water, and dust, virtually every person in America has a detectable level of PFAS in their blood.

Since the release of the updated Health Advisory Levels in June 2022, Thornton has been a leader in the state in addressing the risks of PFAS. 

• Transparently inform the public on PFAS levels in the drinking water and our strategy to address the new regulations.
  
• Procuring laboratory instrumentation to conduct further monitoring of PFAS in our system
  
• Improving current treatment processes and source water blending strategies to reduce PFAS in the drinking water
  
• Procuring engineering and construction consultants to evaluate the effectiveness of preliminary PFAS treatment designs
  
• Entered a multijurisdictional lawsuit against the manufacturers of PFAS for costs related to PFAS treatment
  
• Pursuing grant funding through CDPHE’s State Revolving Fund for PFAS monitoring and treatment
  
• Supporting legislation that removes PFAS from entering the water source and holding polluters accountable
  

Customers concerned about reducing the risk associated with PFAS in their drinking water may install water filters at their homes. Visit the CDPHE website for a list of filters approved for PFAS removal: https://cdphe.colorado.gov/pfas-health.

Customers may also want to consider reducing exposure to PFAS from consumer products such as nonstick pans, take-out food, waterproof clothing/outdoor gear, and cosmetics.

Thornton has received reports of companies using predatory sales tactics to scare customers into paying more than they need to for water treatment options. The filters recommended by CDPHE for PFAS removal range from $50-200: https://cdphe.colorado.gov/pfas-health.

There is a list of everyday items with PFAS and which brands are PFAS-free: https://pfascentral.org/pfas-free-products/.

If you have questions or concerns about your tap water that were not answered here, please email waterquality@thorntonco.gov or call the Water Quality Line at 303-255-7770.