St. Johns Water Hardness & Quality Report (2026)
Water Hardness
7.9 grains per gallon
Source
groundwater
pH Level
7.8
neutral = 7.0
Lead
0.003 mg/L
✓ Below action level
TDS
340.7 mg/L
Est. Daily Cost
$0.36
energy & soap waste
Source: USGS Water Quality Portal · Updated 2026
0–60
mg/L
Soft
61–120
mg/L
Moderately Hard
121–180
mg/L
Hard
180+
mg/L
Very Hard
Appliance Damage Report
In St. Johns, your appliances are currently losing 18% efficiency due to mineral buildup.
| Appliance | In St. Johns | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 5.1 yrs | 8.5 yrs | -40% |
| Washing Machine | 8.6 yrs | 12 yrs | -28% |
| Water Heater | 10.2 yrs | 15 yrs | -32% |
Regional Water Comparison
How St. Johns compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ St. Johns, Florida | 136 mg/L | 6.8 ppt | 🟠 Hard | groundwater |
| Fruit Cove, Florida | 78.5 mg/L | 5 ppt | 🟡 Moderately Hard | groundwater |
| Fleming Island, Florida | 264 mg/L | 10.9 ppt | 🔴 Very Hard | groundwater |
| Palm Valley, Florida | 174 mg/L | 8 ppt | 🟠 Hard | groundwater |
| Bellair-Meadowbrook Terrace, Florida | 290.5 mg/L | 11.7 ppt | 🔴 Very Hard | groundwater |
National Benchmark
How St. Johns compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ St. Johns | 136 mg/L | 🟠 Moderate |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes St. Johns's Water Unique?
Local geology and source profile
St. Johns, Florida, in St. Johns County — a rapidly growing St. Johns County suburban community south of Jacksonville, one of the fastest-growing communities in the entire United States (St. Johns County has been among the fastest-growing counties in Florida and the nation for the 2010s–2020s), a major master-planned community (the Julington Creek Plantation area and Bartram Springs master-planned communities), and a diverse St. Johns County community in the growing Jacksonville south exurban corridor — draws its municipal water supply from the Upper Floridan Aquifer via the St. Johns County Utility (SJCU). Water hardness in St. Johns measures 136 mg/L — classified as moderately hard.
St. Johns' moderate hardness reflects the St. Johns County Floridan Aquifer characteristics and SJCU treatment. The Upper Floridan Aquifer in St. Johns County is hosted in: the Eocene Ocala Limestone (calcareous marine limestone of the Florida Platform); the Avon Park Formation (calcareous dolomite and limestone). SJCU applies moderate treatment including partial lime softening to the raw Floridan Aquifer water (which is typically harder at approximately 200–270 mg/L in this area), producing the moderate 136 mg/L at household taps.
At 136 mg/L, St. Johns residents encounter moderate-to-hard scale accumulation. Monthly descaling with citric acid solution is recommended. SJCU consistently delivers water meeting all Florida DEP and EPA Safe Drinking Water Act requirements.
Geology & Source: Groundwater from the Floridan Aquifer System (Upper Floridan Aquifer) via the St. Johns County Utility (SJCU) or private well — the St. Johns County northeast Florida inland (Eocene Ocala Limestone and Avon Park Formation calcareous limestone karst; moderate Floridan Aquifer supply with partial lime softening); moderately hard supply at 136 mg/L — reflecting northeast Florida's Floridan Aquifer with moderate SJCU treatment.