1. What the Hazard Index Tells Us About Mixed PFAS Compounds
The term PFAS (per- and polyfluoroalkyl substances), also called fluorinated compounds or 'forever chemicals,' encompasses a group of related substances found in water. These substances can occur together in mixtures, and the Hazard Index is a tool that estimates their combined presence's relative significance for evaluation. While hazard indexes are used for assessment, they do not by themselves define if water is safe or unsafe. They serve as a way to understand potential concerns when multiple compounds appear together in water samples.
2. Why PFOA and PFOS Are Reported in Nanograms per Litre with Four Decimals
Measurements of compounds like PFOA and PFOS in water use nanograms per litre (ng/L), equivalent to parts per trillion (ppt), because these substances can be present at extremely low levels. Reporting values to four decimal places, such as 0.0040 µg/L, reflects the precision of federal monitoring methods but does not imply a regulatory threshold has been exceeded. In the Murray City Water System, these low levels have been detected but remain well below federal maximum contaminant levels (MCLs).
3. What Can Occur If PFAS Are Left Untreated Over Years
When PFAS compounds remain untreated in household water, they persist due to their chemical stability, earning the nickname "forever chemicals." While government sampling detects certain PFAS at low levels, prolonged exposure assessments depend on individual water testing. Without treatment, these substances could continue to be present in a home’s supply, but the effects and significance vary widely. Understanding personal water chemistry is essential to guide any response.
4. Distinguishing Public-System Records from Private Well Water Tests
Data for the Murray City Water System represent aggregated sampling from a public groundwater supply serving over 38,000 people through more than 11,500 connections. This system-level data neither predicts nor guarantees PFAS levels in any individual home’s water, especially if private wells or separate sources exist. Only testing of a specific household water source can determine that home’s actual PFAS content.
5. How PFAS Enter Groundwater and the Distribution System in Salt Lake County
PFAS substances commonly enter groundwater through sources such as industrial sites, firefighting foam use, and past chemical applications. The Murray City Water System relies on groundwater, which can reflect broader regional PFAS presence detected via federal monitoring. The actual pathways vary but include historical environmental releases and possibly urban runoff, rather than a single contamination event affecting an individual property.
6. Interpreting Measured PFAS Ranges Against Federal Standards
The 2023-2025 EPA Unregulated Contaminant Monitoring Rule (UCMR5) data for the Murray City Water System show detections of several PFAS compounds with highest reported levels below federal MCLs established in 2024. For example, PFOA was detected once at 0.004 µg/L (4 ng/L), well under the 4.0 ng/L MCL. Other substances like PFHxS and PFBS appeared only in trace amounts. These findings indicate the system’s PFAS concentrations remain within federal guideline limits but do not define the concentration inside any one household.
For households facing water treatment equipment failure and concerned about PFAS, testing the household water directly is the next step to understand specific effects. The Pentair PFAS Forever Chemicals Filter offers a documented approach to reduce these compounds at the point of use, shipping ready to configure for residential application.
The information here relates exclusively to the Murray City Water System’s publicly reported sampling results for Salt Lake County and does not predict individual home water quality. For reference and more details, consult the EPA’s public water system records and the UCMR5 monitoring data directly.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2025-02-03. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR5 monitoring (2023-2025) for MURRAY CITY WATER SYSTEM (UTAH18024), UT: 380 results across 10 listed contaminants, 23 detections above the reporting level; compared with the applicable federal MCL, none above