Charleston, South Carolina
Water Filtration Systems in Charleston
Soft water, chloramine, and PFAS above the coming federal limit.
Soft water, chloramine, and PFAS above the coming federal limit.
Quick answer: Charleston is served by Charleston Water System, which treats surface water from Bushy Park Reservoir and the Edisto River and disinfects with chlorine dioxide and chloramines. Its water is soft — the utility publishes 58.4 ppm and calls it moderately soft — so a softener is rarely justified. PFOA and PFOS both measured above EPA’s new 4.0 ppt limits, which is the problem worth solving. Call (843) 718-8177.
Charleston Water System serves the peninsula, West Ashley, much of James Island and a good deal beyond, and it publishes a great deal about its own water. The figures below are all theirs or EPA’s.
| Measure | Published figure | Source |
|---|---|---|
| Hardness | 58.4 ppm · 3.4 grains — “moderately soft” | Charleston Water System FAQ · 2026 |
| Source water | 90% Bushy Park Reservoir, 10% Edisto River | Charleston Water System FAQ · 2026 |
| Disinfectant | Chlorine dioxide and chloramines | Charleston Water System FAQ · 2026 |
| PFOA / PFOS | 4.3 / 5.8 ppt — both above the 4.0 limit | EPA UCMR5 occurrence data · 2026-08 |
| Total trihalomethanes | 12 ppb against an 80 ppb limit | CWS 2026 Water Quality Report · 2026 |
| Lead, 90th percentile | 3.5 ppb against a 15 ppb action level | CWS 2026 Water Quality Report · 2026 |
Every figure above is published by Charleston Water System or by EPA. None of it is our measurement, and all of it is checkable.
The utility calls its own water moderately soft and publishes 3.4 grains per gallon. National softener retailers advertise Charleston at 8.5 to 10.2 grains. There is very little hardness here to remove.
Because the disinfectant is chloramine rather than free chlorine, ordinary carbon needs about ten minutes of contact time to strip it and catalytic carbon needs three to four. Most systems sold here are sized for neither.
PFOA and PFOS both measured above the new federal limits. Those limits are not enforceable until April 2029, so the utility is not in violation — but an under-sink reverse osmosis unit addresses it now for a few hundred dollars.
Charleston Water System has about 6,000 lead service lines left, concentrated in the Neck area of North Charleston and on the peninsula between Cosgrove Avenue and the Battery. It notified 70,000 customers in November 2024 and is replacing them under a ten-year programme.
The water leaving the plant has no lead in it — the utility’s 90th-percentile result is 3.5 ppb against a 15 ppb action level, and corrosion control has been running since 1992. But if your service line is on that list, a certified point-of-use filter at the kitchen tap is a reasonable thing to want in the meantime.
Permits in Charleston go through City of Charleston; the licensed plumbing subcontractor pulls it in their own name.
Soft. Charleston Water System publishes 58.4 ppm, or 3.4 grains per gallon, and describes its own water as moderately soft.
USGS classifies anything below 60 mg/L as soft. Retailers advertising Charleston at 8.5 to 10.2 grains are roughly three times over the utility’s own figure.
Yes — EPA measured PFOA at 4.3 and PFOS at 5.8 parts per trillion, both above the federal limit of 4.0.
Charleston Water System publishes the same numbers in its own report. The limits are not enforceable until April 2029, so the utility is not in violation.
Catalytic carbon for the chloramine if you want the whole house treated, and an under-sink reverse osmosis unit for PFAS.
Ordinary carbon is poor at chloramine at residential tank sizes. A softener is not indicated on this water.