How Hard Is the Water North of Orlando?

If your shower door grows a white haze no matter how often you wipe it, you are seeing the aquifer at work. The raw groundwater our utilities pump carries the calcium and magnesium that cause water hardness, and the treatment steps the local reports describe mostly target sulfur smell and germs, not minerals.

What makes our tap water hard?

Hardness is dissolved calcium and magnesium, picked up as water moves through the limestone of the Floridan aquifer system. Every utility serving Seminole and north Orange County pumps from that aquifer, so the minerals arrive at every plant. A few plants change the picture a little: Seminole County's Northwest service area uses ion exchange along with ozone, and Winter Springs uses ion exchange at its Plant #1 to cut organic carbon. None of the reports we read claims to soften water for the whole system.

How hard is it, town by town?

Only two suppliers publish a number. OUC says its water averages 129 ppm, or 7 grains per gallon; converting at 17.1 mg/L per grain puts OUC nearer 7.5 grains per gallon. Winter Springs has stated an average of 150 mg/L, close to 8.8 grains per gallon by the same math, though the city itself says 8.

On the USGS hardness scale, water from 121 to 180 mg/L counts as hard, and anything above 180 mg/L is very hard. Both local figures fall inside the hard band, OUC near its bottom edge and Winter Springs closer to the middle.

Average hardness in mg/L as calcium carbonate; USGS band edges for comparison

OUC average129 mg/L

Winter Springs average150 mg/L

USGS hard band starts121 mg/L

USGS very hard above180 mg/L

Source: Orlando Utilities Commission; City of Winter Springs (archived page); USGS Water Science School

The others do not publish hardness at all. Oviedo, Altamonte Springs, Longwood, Lake Mary, Sanford, Orange County Utilities and Seminole County Utilities all leave it out of their yearly reports, and Casselberry's report could not be read. That does not mean their water is soft; it means nobody has printed the number.

Grains or milligrams: which number matters?

Both describe the same thing, so pick whichever your test kit or salesperson uses and convert. One grain per gallon equals 17.1 mg/L. Penn State Extension's water softening page uses grains and sets its own bands, and it notes that water under 7.0 grains per gallon will probably not cause major scaling and soap film.

What does hard water do around the house?

It leaves minerals wherever water heats up or dries out. A. O. Smith's water heater manual says tap water minerals form lime on heating elements and sediment in the tank, and in very hard water it says to check the elements every time the tank is drained. Tankless heaters are touchier. Rinnai's V53e manual says hard-water installs must be treated or flushed regularly, puts the hardness ceiling at 200 mg/L, and does not cover heat-exchanger damage caused by water quality under warranty. Our water heaters story covers flushing and the 120°F setting.

How can you find your own number?

On city or county water, call the utility and ask for its average total hardness, or check its yearly water quality report in case a newer edition adds it. Home test strips give a rough reading in grains per gallon. On a private well, include hardness when you send a sample to a state-certified lab; the private wells story explains how the county health department handles testing.

Is a softener worth it at these levels?

That depends on your number and on what bothers you. A test should show your total hardness in grains per gallon before anyone quotes equipment: By Penn State's yardstick, scaling is unlikely to be major below 7.0 grains, and both published local figures, about 7.5 grains (OUC) and 8.8 grains (Winter Springs), sit above that. Sanford's FAQ adds two cautions: softened water is more corrosive to indoor pipes and adds sodium, which matters for anyone watching blood pressure. The water softeners story goes through those trade-offs.

Readers often ask

Is Lake Mary water hard?

Lake Mary's 2025 report does not list hardness. Its wells draw from the upper Floridan like everyone else's, so ask the city's public works office for a figure or run a home test.

Why does my utility leave hardness out of the report?

The reports we read simply don't include it, apart from the two figures OUC and Winter Springs have put out. A phone call to the utility is the quickest way to get a number.

Is 7 grains per gallon a lot?

Penn State puts 7.0 to 10.5 grains in its hard class and says water below 7.0 probably won't cause major scaling. OUC's figure sits right at that line.

Does hard water hurt a tankless water heater?

It can. Rinnai's V53e manual lists a 200 mg/L hardness limit, shows a scale code when buildup affects performance, and excludes water-quality damage to the heat exchanger from the warranty.

Do Winter Springs and OUC numbers mean the same thing?

Yes, both are averages of total hardness. Winter Springs has stated 150 mg/L and OUC 129 ppm (the same as mg/L), so Winter Springs water runs somewhat harder.

Where this came from

1. USGS — Hardness of Water — hardness classes in mg/L
2. Orlando Utilities Commission — Water quality reports and FAQ — OUC average hardness
3. City of Winter Springs — Potable (Drinking) Water, archived copy — 150 mg/L average hardness
4. City of Sanford — Drinking Water FAQ — raw water minerals; softener cautions
5. USGS — Floridan aquifer system, Seminole County (WRI 01-4182) — the aquifer as the local source
6. Penn State Extension — Water Softening — grains-per-gallon classes and the 7.0 gpg note
7. A. O. Smith — Electric water heater manual — lime and sediment from hard water
8. Rinnai — V53e installation and operation manual — tankless hardness limit and warranty