Federal monitoring data shows that Toho Water Authority, which delivers drinking water to roughly 40,330 customers in Kissimmee and Osceola County, detected PFOS at 4.1 and 4.2 parts per trillion at one of its sampling points during EPA UCMR 5 testing in 2024. The EPA's April 2024 final rule set a maximum contaminant level of 4 parts per trillion for PFOS. That detection is above the limit, but water systems nationwide have until April 2029 to achieve compliance, and the detection does not constitute a current regulatory violation. Toho has no health-based Safe Drinking Water Act violations on record. Understanding what this monitoring data means, and what it does not mean, is essential before making any treatment decisions for a Kissimmee home.
What is PFOS, and why did EPA set a 4 ppt limit?
PFOS, or perfluorooctane sulfonic acid, is one of the most studied compounds in the per- and polyfluoroalkyl substances (PFAS) family. It was the primary active ingredient in Scotchgard fabric protector until 3M voluntarily phased it out in 2002, and it was used extensively in aqueous film-forming foam (AFFF) for firefighting, particularly at military installations and airports. PFOS is persistent: it does not break down readily in the environment or in the human body, and it bioaccumulates over time.
In April 2024, the U.S. Environmental Protection Agency finalized the first-ever national drinking water standards for PFAS compounds, setting maximum contaminant levels (MCLs) of 4 parts per trillion for both PFOS and PFOA individually, and 10 parts per trillion for a combined hazard index covering three additional PFAS. The EPA estimates the rule will prevent thousands of serious illnesses annually (EPA, PFAS in Drinking Water, 2024). Water systems have until April 2029 to comply.
The MCL of 4 ppt is the lowest level EPA determined was achievable by large water systems while remaining technically and economically feasible. It is also a health-based limit: EPA's maximum contaminant level goal (MCLG) for PFOS is zero, reflecting the agency's position that no safe threshold has been established for PFOS exposure over a lifetime. The difference between the goal (zero) and the MCL (4 ppt) reflects the practical limits of treatment technology, not evidence that water at 4 ppt is harmless.
What EPA UCMR 5 monitoring found at Toho Water Authority
The EPA's Unregulated Contaminant Monitoring Rule 5 (UCMR 5) required large public water systems to test for 29 PFAS compounds between 2023 and 2025. Toho Water Authority conducted five sampling events at its Western system (PWSID FL3491011) serving Kissimmee. The full dataset is publicly available through the EPA UCMR 5 Data Finder (EPA, UCMR 5, epa.gov).
Of 116 total monitoring records across all compounds and sampling points, two results exceeded the minimum reporting level for PFOS at a single sampling point (1011001).
| Sample date | Sampling point | Compound | Result | EPA MCL |
|---|---|---|---|---|
| May 2024 | 1011001 | PFOS | 4.2 ppt | 4 ppt |
| December 2024 | 1011001 | PFOS | 4.1 ppt | 4 ppt |
A second sampling point (1011002) tested negative for PFOS detections above the minimum reporting level across its rounds. Toho's Southern system serves the St. Cloud and southern Osceola County area; this data covers the Western system serving Kissimmee, Celebration, and nearby communities. Toho began voluntary PFAS sampling in June 2023 and publishes ongoing results at tohowater.com/our-water/pfas-and-developing-regulations.
What this means for Kissimmee homeowners
Detection above the MCL in UCMR 5 monitoring is not the same as a Safe Drinking Water Act violation. UCMR 5 is a surveillance program; it generates the data that regulators and water systems use to plan compliance. Toho has until April 2029 to reduce PFOS to or below 4 ppt at all sampling points. The system has no health-based violations on record in EPA's Safe Drinking Water Information System (SDWIS) database (EPA ECHO database).
What the data does tell homeowners: PFOS is present in at least one part of the Kissimmee distribution system at concentrations near the regulatory threshold. The values detected, 4.1 and 4.2 ppt, are marginally above the MCL and well below the concentrations associated with short-term acute risk. The EPA's health advisory levels prior to the 2024 rule were considerably more permissive; the new MCL of 4 ppt reflects a more precautionary standard.
For most Kissimmee city water customers, the practical takeaway is: this data warrants attention, not alarm. The appropriate response is the same one that applies to any drinking water quality concern: verify, then treat if you choose to.
What treatment removes PFOS from tap water
Two technologies are well-established for removing PFAS including PFOS from drinking water at the point of use. Granular activated carbon (GAC) and reverse osmosis (RO) are both recognized by the EPA and the NSF as effective treatment approaches.
Reverse osmosis is the more comprehensive option for a residential tap. A properly installed under-sink RO system pushes water through a semi-permeable membrane that blocks PFAS molecules along with nitrates, heavy metals, and most dissolved solids. NSF/ANSI Standard 58 covers RO systems for drinking water; products certified to that standard have been tested for contaminant reduction including PFAS. An RO unit treats water at the kitchen faucet only, not whole-house. For drinking and cooking, that is the tap that matters most.
Whole-house GAC filtration reduces PFAS across all taps but is less efficient per gallon than RO at very low concentrations. It is appropriate where whole-house PFAS reduction is a priority, particularly for households where shower or bath exposure is a concern. Carbon filter performance degrades over time; media replacement schedules matter and vary by contaminant load and water volume.
Any water treatment system claiming to remove PFAS should carry NSF/ANSI certification for that specific claim. Pure Agua Enterprises is NSF/WQA certified and FL licensed, and can assess which treatment configuration fits your specific Kissimmee address based on a water test. Call (407) 773-2883 or schedule a free water test online to get started.
What about Kissimmee water hardness?
PFOS is one part of the Kissimmee water quality picture. The other constant factor for Osceola County homeowners is hard water.
Toho Water Authority draws from the Upper Floridan Aquifer, the same limestone-filtered groundwater source used by most Central Florida utilities. Water hardness in Toho's service area runs in a similar range to neighboring OUC and Orange County Utilities, typically 150 to 200 milligrams per liter as calcium carbonate, or roughly 9 to 12 grains per gallon (City Desk Orlando, July 2026). The Water Quality Association classifies water above 10.5 GPG as very hard (WQA Water Hardness Scale). At those concentrations, scale accumulates in water heaters, dishwashers, and plumbing. A water softener addresses hardness; it does not address PFOS. If both concerns apply to your home, a softener plus an under-sink RO system is the standard combination.
What Kissimmee well owners should know
Private well owners in Osceola County are not covered by Toho Water Authority monitoring and do not receive Consumer Confidence Reports. UCMR 5 and SDWIS data covers public water systems only.
PFAS can reach private wells through legacy contamination: historical AFFF foam use at nearby airports or military sites, industrial discharge, or movement through permeable Florida soils. Homeowners on private wells who want to know their PFAS status need to commission a certified laboratory test. The Florida Department of Health's private well guidance is available at floridadep.gov. Well owners in areas near Kissimmee Gateway Airport or agricultural operations should consider PFAS testing a reasonable precaution.
How to verify your own Kissimmee water data
Toho Water Authority publishes annual Consumer Confidence Reports for its Northern, Southern, Central, and Western systems. Each report covers the prior calendar year's testing and is required to be delivered to customers by July 1. Past reports are available at tohowater.com/our-water/water-quality-reports. UCMR 5 data for any public water system is searchable through the EPA's public UCMR 5 Data Finder tool. Toho's PWSID is FL3491011 for the Western system and FL3491012 for Southern.
A free in-home water test from Pure Agua Enterprises measures hardness, pH, chlorine or chloramine residual, iron, and total dissolved solids. It does not test for PFAS, which requires a certified laboratory. If PFAS is a specific concern, we can provide a referral to a Florida-certified laboratory. Call (407) 773-2883 or use the contact form to schedule a free in-home assessment across Kissimmee, St. Cloud, Celebration, Poinciana, and surrounding Osceola County communities.
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