Summerville, South Carolina
Water Filtration Systems in Summerville
The softest public water in the Lowcountry — and PFAS above the federal limit.
The softest public water in the Lowcountry — and PFAS above the federal limit.
Quick answer: Summerville CPW supplies Lake Moultrie water through Santee Cooper’s regional plant. At 23 ppm, about 1.35 grains, it is the softest public supply in the Lowcountry — a softener here would have almost nothing to remove. EPA measured PFOA at 5.7 and PFOS at 6.7 parts per trillion, both above the 4.0 federal limit. Call (843) 718-8177.
Summerville is on a completely different watershed from Charleston. Its water comes from Lake Moultrie through Santee Cooper’s regional plant, and the numbers are correspondingly different.
| Measure | Published figure | Source |
|---|---|---|
| Hardness | 23 ppm · 1.35 grains — softest in the Lowcountry | Summerville CPW 2025 Water Quality Report · 2025 |
| Source water | Lake Moultrie, via Santee Cooper’s regional plant | Santee Cooper regional water systems · 2026 |
| Disinfectant | Chloramine at the plant; free chlorine in distribution | Santee Cooper regional water systems · 2026 |
| PFOA / PFOS | 5.7 / 6.7 ppt — both above the 4.0 limit | EPA UCMR5 occurrence data · 2026-08 |
| Total trihalomethanes | 30 ppb against an 80 ppb limit | CWS 2026 Water Quality Report · 2026 |
| Lead, 90th percentile | 0.9 ppb; no lead service lines reported | CWS 2026 Water Quality Report · 2026 |
All figures published by Summerville CPW, Santee Cooper or EPA.
At 1.35 grains per gallon this is the softest public water in the region. There is essentially no hardness to remove, and anyone selling a softener in Summerville should be asked for their number.
Both regulated compounds measured above the federal limits — PFOA higher here than in Charleston. Not enforceable until April 2029, and addressable now with an under-sink reverse osmosis unit.
Trihalomethanes at 30 ppb against a limit of 80 — about two and a half times Charleston’s level, because of the different source and treatment. Carbon handles these, and it is one of the things a whole-house system is genuinely good at.
Permits in Summerville go through Town of Summerville; the licensed plumbing subcontractor pulls it in their own name.
No — at 23 ppm, about 1.35 grains per gallon, it is the softest public supply in the Lowcountry.
That is well under half of Charleston’s figure and comfortably inside the USGS soft band. A softener would have almost nothing to do.
Yes. EPA measured PFOA at 5.7 and PFOS at 6.7 parts per trillion, both above the federal limit of 4.0.
PFOA is actually higher in Summerville than in Charleston. The limits are not enforceable until April 2029, so Summerville CPW is not in violation.
Lake Moultrie, treated at Santee Cooper’s regional plant — a different source from Charleston’s.
Goose Creek, Moncks Corner and much of Berkeley County drink the same water, which is why their published figures match Summerville’s rather than Charleston’s.