Water hardness in St. Petersburg FL
9.2 gpg hard
Tap water in St. Petersburg FL is hard: 9.2 gpg (158 mg/L · 8.9 °dH · 15.8 °fH).
Source: City of St. Petersburg Water Quality Report 2025-26 (2025) · data checked 2026-10-19
The City of St. Petersburg's 2025-26 water quality report gives hardness of 158 mg/L (9.2 gpg), the average of monthly samples taken in 2025. It is one system-wide figure with no zone split. That is hard water, so expect visible scale on kettles, shower screens and water heaters.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 9.2 gpg |
|---|---|
| Utility | City of St. Petersburg Water Resources |
How St. Petersburg FL compares
- Tap water in St. Petersburg FL is close to the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 680 of 1372 in the United States (1 = hardest); 50 % of these cities have softer water.
- In Florida it is number 7 of 17 cities; the regional median is 8.2 gpg.
- Nearest city with clearly softer water: Cape Coral FL, 150 km away (6 gpg).
- Nearest city with clearly harder water: Pinellas Park, 12 km away (12.7 gpg).
Ranking of the hardest and softest water in the United States →
What it means at home
- Fast scale on taps, shower screens and kettle; white spots on glassware.
- Water heater: efficiency loss and element failures within years if unprotected.
- Dry skin and dull hair after showering are common.
- Softener recommended; jug or reverse osmosis for drinking.
How much salt will you use for softening?
Recommended, especially with a heater or boiler: scale cuts efficiency and shortens its life.
Descale a coffee machine or kettle about every 2 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in St. Petersburg FL
| Brand | Setting for this water |
|---|---|
| Bosch | H02 |
| Miele | 9 °dH |
| AEG / Electrolux | 2 |
| Beko | 3rd |
| Hoover | S1 |
| LG | H2 |
From each brand's manual for the model family named in the source; your model may differ, so check its manual. All brands and how to change the setting →
FAQ
Is St. Petersburg FL water hard or soft?
It is hard: 158 mg/L as CaCO₃ (9.2 gpg, 8.9 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in St. Petersburg FL safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
How many grains per gallon is St. Petersburg FL water?
9.2 gpg, equal to 8.9 °dH, 15.8 °fH or 158 mg/L calcium carbonate.
What dishwasher salt setting should I use in St. Petersburg FL?
For 158 mg/L (8.9 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in St. Petersburg FL?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: City of St. Petersburg Water Quality Report 2025-26 (2025). Method: figure published by the water supplier. City of St. Petersburg Water Quality Report 2025-26 · Outdated figure? Tell us