Where the minerals come from
The Biscayne Aquifer is porous limestone, and groundwater picks up calcium as it moves through it. At the Alexander Orr, Jr. plant, WASD adds lime to soften the water; the sediment settles out as lime sludge before the water is filtered and disinfected. What remains at your faucet varies, and WASD's report doesn't list a single hardness figure for homes.
Water from a private well skips that plant softening entirely, so well homes often see heavier scale than neighbors on county water.
Where you see it
- Glass shower doors and mirrors.
- Faucet aerators and shower heads.
- Dishwasher glassware.
- Inside the water heater and tankless units.
- Outdoors: pool tile lines and car finishes washed with hose water.
Test before you treat
Jorge measures hardness and dissolved solids at your tap. If it's low, spots are a cleaning habit issue. If it's higher, a softener may be worth it. If you're on a private well, hardness is usually higher than county water.
He also asks how quickly spots appear and where; that pattern often says as much as the number.
Softener vs. conditioner
| Ion-exchange softener | Salt-free conditioner | |
|---|---|---|
| Removes hardness | Yes | No, changes how it behaves |
| Spots on glass | Reduced | May still appear |
| Discharge | Brine | None |
On a South Miami property still on septic, brine discharge needs planning. See conditioner vs. softener.
Jorge explains both after measuring, and recommends neither if your number is low.
Scale and your appliances
Scale builds where water is heated: tank water heaters, tankless units, coffee makers and dishwashers. A tankless heater's maker usually recommends periodic flushing; follow it. If your test shows significant hardness, softening reduces how fast that buildup returns.
Pools, cars and the outdoors
Outside, hose water from the county line carries the same minerals, so pool tile lines and cars washed in the driveway can spot. If your sprinklers run from a private well, hardness and iron in that water are usually higher and can leave white or orange residue on walls and walkways. See orange stains in South Miami for the iron side.
Habits that help
- Squeegee glass after each shower.
- Soak aerators and shower heads in vinegar periodically.
- Use a rinse aid in the dishwasher.
Call, text or WhatsApp (305) 793-5974 for a free hardness test.
If spots return within days despite these habits, that's a sign hardness at your tap is high enough to measure and treat.
https://www.miamidade.gov/resources/water/documents/2025-water-quality-report.pdf
https://www.southmiamifl.gov/806/Septic-to-Sewer-Information
Updated 2026-10-17 · Living Waters · Jorge Canela, Water Quality Specialist