This is one of the most-Googled water questions in the Lowcountry right now. And the answer isn't simple, because the question sits at the intersection of two different standards for what's "safe."
Here's the cited data. Every number links to its source. We don't editorialize the science. We read the public record and tell you what it says.
The Short Answer
Per EWG's 2014-2023 testing of Summerville CPW data, PFUnA (a compound in the PFAS family) was measured at roughly 1,183 times EWG's health advisory guideline, and PFDoA (another PFAS compound) at roughly 75 times their guideline.
Both readings are legal under current federal standards. The EPA finalized its first-ever national PFAS maximum contaminant level in April 2024, setting the limit for PFOS and PFOA at 4 parts per trillion (ppt). Summerville CPW's raw intake from Lake Moultrie has measured 7 ppt PFAS at the source.
EWG's position is that federal limits are too lenient. The EPA's position is that their limits are enforceable and science-based. Both positions are published. We point you to both and let you decide.
What CPW is Doing About It
Summerville CPW is investing about $43.5 million as its share of a $96 million regional PFAS treatment project. This is a utility-level infrastructure project to treat the water at the plant before it reaches your home.
Alongside the PFAS project, CPW implemented a 12.2% rate hike for customers. The rate increase funds the PFAS treatment and other infrastructure upgrades.
The federal compliance deadline for PFAS treatment is 2029.
The EWG Numbers in Context
Here's what EWG specifically flagged on Summerville CPW, with the measured levels and the EWG guideline multiples:
| Compound | Type | Measured Level | EWG Multiple |
|---|---|---|---|
| PFUnA | PFAS | 7.1 ppt | 1,183x |
| PFDoA | PFAS | 4.50 ppt | 75x |
These are the two PFAS-category compounds EWG flagged for CPW. The other 9 EWG flags are disinfection byproducts (TTHMs, HAA9, HAA5, etc.) and chromium (hexavalent).
Important: EWG guidelines are not regulatory limits. They're EWG's assessment of newer health research applied to water quality data. The EPA's MCLs are the enforceable limits. Both are public.
How This Compares to Charleston Water System
Charleston Water System (CWS), which serves peninsular Charleston, James Island, West Ashley, and parts of Mount Pleasant, has its own PFAS story.
CWS tested for PFAS voluntarily starting in 2017. The December 2023 PFOS reading was 5.56 ppt. The March 2025 reading was 5.7 ppt PFOS and 4.4 ppt PFOA. Both PFOS and PFOA are above the 4 ppt EPA MCL.
CWS is budgeting approximately $130 million for PFAS treatment infrastructure, with annual operating costs of $10-12 million. A 5% rate increase is already in effect, with another 10% planned for 2026.
Mount Pleasant Waterworks measured 8.4 ppt PFOS and 5.5 ppt PFOA in November 2024, both above the EPA MCL.
Every Lowcountry utility is dealing with this. Summerville CPW isn't unique. The question is what each utility is doing about it and on what timeline.
What This Means for Your Home
The PFAS treatment projects at CPW and CWS are utility-level infrastructure. They're designed to reduce PFAS at the treatment plant before the water reaches your distribution pipe.
At the household level, point-of-use reverse-osmosis systems are the typical response for homeowners who want additional reduction at the drinking-water tap. A POU RO unit installs under your kitchen sink with a dedicated faucet and addresses contaminants at a tap-by-tap level.
The effectiveness of any specific POU system depends on its certification scope. Not every RO unit on the market is certified for every PFAS compound. The certification matters.
We're transparent about this: a whole-home conditioning system is designed for aesthetic water treatment (hardness, chlorine, sediment). Specific contaminant reduction at the drinking-water level is a POU conversation. We'll walk you through the certification scope of any equipment we recommend, and we won't claim something we can't substantiate.
What "PFAS" Actually Means
PFAS stands for per- and polyfluoroalkyl substances. There are thousands of individual PFAS compounds. They're called "forever chemicals" in media coverage because the carbon-fluorine bond in their molecular structure is extremely stable and resists natural breakdown.
The two most-studied PFAS compounds are PFOS (perfluorooctane sulfonic acid) and PFOA (perfluorooctanoic acid). The EPA's April 2024 MCL targets these two at 4 parts per trillion each.
PFUnA and PFDoA, the two compounds EWG flagged on Summerville CPW, are different members of the PFAS family. They're less studied than PFOS and PFOA. EWG's guidelines for these compounds are based on their current assessment of the available toxicology research.
The science is evolving. The regulation is evolving. What's not evolving is the public data: CPW publishes their readings, EWG compiles them, and both are accessible to anyone who wants to read them.
The Rate Hike Context
CPW implemented a 12.2% rate hike alongside the PFAS project announcement. For a typical residential customer, that translates to a meaningful increase in the monthly water bill. The rate increase funds the $43.5 million CPW share of the $96 million regional project plus other infrastructure maintenance.
Rate hikes are never popular. But the alternative, deferred maintenance on a water system serving a rapidly growing population, carries its own risks. The March 2026 boil-water advisory was a reminder of what happens when infrastructure meets stress.
FAQ: PFAS in Summerville Water
Is CPW water illegal because of PFAS?
No. CPW water meets current EPA limits. The PFAS MCL that the EPA finalized in April 2024 has a compliance deadline of 2029. CPW is investing in treatment infrastructure ahead of that deadline.
Should I stop drinking tap water?
That's a personal decision. The water is legally compliant. If the EWG data concerns you, there are household-level options at the drinking-water tap. A free water test is a good starting point for understanding what's in your specific tap.
Can a home water system handle PFAS?
Certain point-of-use reverse-osmosis systems are certified for specific PFAS compounds under NSF/ANSI standards. The certification varies by model and manufacturer. Not every system on the market can make that claim. We'll show you the certification scope for any system we recommend.
How does Summerville's PFAS situation compare to Charleston's?
Charleston Water System measured 5.7 ppt PFOS and 4.4 ppt PFOA in March 2025, both above the EPA's 4 ppt MCL. CWS is budgeting $130 million for PFAS treatment. Mount Pleasant Waterworks measured 8.4 ppt PFOS and 5.5 ppt PFOA in November 2024. Every Lowcountry utility is facing some version of this issue.
If You Want to See Your Own Numbers
Book a free in-home water test. I'll test your tap, compare the results to the utility-level data, and walk through what the numbers mean for your household. No obligation.
If your water's fine, I'll say so. If specific contaminants concern you, I'll walk through the POU options and their certification scope.
Call or text Jarred at (843) 302-5720, or book at prstnwtr.com/book.