Contaminants & Tech
Two terms show up constantly in water quality conversations right now: PFAS and TDS. They're not the same thing, and they call for different solutions.
PFAS, often called “forever chemicals,” are a large family of manmade compounds used for decades in things like nonstick coatings, stain-resistant fabric, and firefighting foam. They don't break down naturally, which is how they end up in waterways and, eventually, drinking water supplies. In 2024, the EPA set the first-ever enforceable national limits for several PFAS compounds, and utilities nationwide have until 2029 to fully comply.
Federal testing under the EPA's fifth Unregulated Contaminant Monitoring Rule screens public water systems for 29 different PFAS compounds. It's a genuinely large family of chemicals, not just the two most talked about (PFOA and PFOS) — and the new federal limit is strict: 4 parts per trillion for those two compounds individually, which is an extraordinarily small concentration to regulate at all. That strictness is itself a signal of how seriously regulators now treat this class of chemical.
South Carolina's environmental agency has been testing PFAS levels at public water systems across the state since 2020, and federal monitoring conducted between 2023 and 2025 has turned up low-level PFAS detections at a number of South Carolina utilities. Being below the legal limit doesn't mean zero — it means the amount detected falls under what regulators currently consider actionable.
A 2025 national analysis of waterways by the Waterkeeper Alliance specifically flagged South Carolina, alongside Michigan and North Carolina, as having some of the higher PFAS levels detected in the country's surface waters. That's a different measurement than a finished tap water sample, but source water quality is exactly where a treated water supply starts — it's the raw material every utility in the state is working from.
Total Dissolved Solids (TDS) is a measure of everything mineral and salt dissolved in your water — calcium, magnesium, sodium, and more. High TDS isn't automatically a health violation, but it directly affects taste, and it's a major contributor to the same scale buildup that damages water heaters and appliances over time.
TDS is measured in parts per million, and most municipal water in the Midlands falls somewhere in a moderate range — noticeable in taste and scale formation, but not extreme. Well water can run higher or lower depending on the specific aquifer. Either way, TDS is one of the easiest numbers to actually measure on the spot, which is why it's one of the first readings we take during a free water test.
Standard carbon pitcher filters are designed to improve taste and odor by targeting chlorine — they were never engineered to reduce PFAS or lower TDS. Reverse osmosis is the standard, well-documented approach for both: it uses a semipermeable membrane fine enough to reject PFAS compounds and dissolved solids that carbon alone simply passes through.
Carbon filtration works by adsorption — contaminant molecules stick to the surface of activated carbon as water passes through. It's effective for chlorine and many organic compounds, but dissolved mineral salts and many PFAS compounds pass right through that same carbon bed. Reverse osmosis works on a completely different principle: it physically forces water through a membrane with pores small enough to block dissolved solids and PFAS molecules from passing at all, rather than hoping they stick to something on the way by. That's the actual engineering reason RO is the recommended treatment for both problems, not a marketing preference.
If you're not sure what's actually in your water, that's the first thing a free in-home test settles — before you spend money on a filter that isn't built for the problem you actually have.
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