Tampa Bay water, explained: hardness, chlorine, and the seasonal switch

Most of our service area sits on top of limestone, and groundwater picks up calcium and magnesium as it moves through it. Add in a blend with surface water from the Hillsborough River and Tampa Bay Water's regional system, and the result is water that measures hard almost everywhere we work.

"Hard" isn't a health term — it's a measurement of dissolved calcium and magnesium, expressed in grains per gallon (gpg). The U.S. Geological Survey calls anything over 7 gpg "hard" and over 10.5 gpg "very hard."

A few utilities publish an exact number in their annual water quality report. Most don't — hardness is an aesthetic measurement, not a regulated one, so Florida doesn't require it in a Consumer Confidence Report (CCR). Where we don't have a published number, we say so and measure it for real at your free in-home test.

• City of Tampa: 12.3 gpg / 211 mg/L (City of Tampa, 2025 water quality report)
• Pinellas County Utilities: 10.2–14.0 gpg (Pinellas County, 2021 CCR)
• St. Petersburg: about 9.2 gpg / 158 mg/L (City of St. Petersburg, 2025–26 water quality report)
• Hillsborough County, Pasco County, Hernando County, and Brooksville: not published — estimated at your free test

Chlorine and chloramine are both EPA-compliant disinfectants used to keep water safe as it travels through pipes. Chloramine (chlorine plus ammonia) holds its disinfecting power longer over long distances, which is why most of our region's utilities use it as their everyday disinfectant.

Hernando County (HCUD), the City of Brooksville, and the cities of Plant City, Oldsmar, Dunedin and Tarpon Springs are exceptions: each draws its water from its own groundwater wells, with no surface-water blend, and disinfects with straight chlorine year-round — never chloramine.

Neither disinfectant is a safety concern at the levels utilities report. This is a taste-and-filtration distinction, not a health one.

Tampa Bay Water, the regional wholesaler for Hillsborough, Pasco, and Pinellas counties plus the cities of Tampa, St. Petersburg, and New Port Richey, blends groundwater, surface water, and desalinated water — and that blend shifts through the year (Tampa Bay Water, "About" page). That's a real reason your water can taste or feel a little different from one month to the next, even with no change at your tap.

If hardness is your main complaint — spots, scale, soap that won't rinse clean — start with our softener vs. conditioner guide. If it's taste or smell from chloramine or chlorine, our chloramine-and-chlorine-switches guide covers what handles each.