How to Test Your Water for Hardness and Iron (Before You Get a Softener Quote)
Every softener quote is built on two numbers: your hardness and your iron. If a salesperson tests your water in the kitchen and you never see the numbers, you can't check whether the system is sized right. This page shows the cheap ways to get those numbers yourself, what each method can and can't tell you, and what the results mean.
Step 1: If you're on city water, read your free report first
Every public water system has to publish an annual water quality report (also called a Consumer Confidence Report). Many list hardness.
- City of Tampa: the 2025 report says the average total hardness of Tampa's finished water was 211 mg/L, or 12.3 grains per gallon, with an average pH of 7.88.
- Unincorporated Hillsborough County (including many Riverview addresses): the County runs 11 separate water systems, each with its own report. Use the County's address map to find yours, then look for hardness or calcium in the tables.
- Tampa Bay Water is the wholesale supplier to Hillsborough, Pasco and Pinellas utilities; your local utility's report is the one that matches your tap.
A utility average is a good starting point, but it's an average. Hardness can vary by source and season, so a home test is still worth doing before you buy.
Step 2: Know what the numbers mean
Hardness is mostly calcium and magnesium, reported as mg/L (same as ppm) "as calcium carbonate," or as grains per gallon (gpg). 1 gpg = 17.1 mg/L. The U.S. Geological Survey's general scale:
| USGS class | mg/L as CaCO₃ | Grains per gallon (approx.) |
|---|---|---|
| Soft | 0 to 60 | 0 to 3.5 |
| Moderately hard | 61 to 120 | 3.6 to 7.0 |
| Hard | 121 to 180 | 7.1 to 10.5 |
| Very hard | More than 180 | More than 10.5 |
By that scale, Tampa's reported 12.3 gpg average is "very hard."
For iron and manganese, the EPA's secondary (non-enforceable, cosmetic) standards are 0.3 mg/L iron and 0.05 mg/L manganese. Above those, EPA lists rusty color, metallic taste and orange or reddish staining for iron, and black or brown staining for manganese. Iron also counts against a softener's capacity, which is why our sizing guide adds it to hardness.
Step 3: Pick a test method
| Method | What it measures | Good for | Watch out for |
|---|---|---|---|
| Hardness test strips | Total hardness, by color match | Quick yes/no, and checking that a softener is working (treated water should read near zero) | Color matching gives a range, not an exact number |
| Drop-count titration kit (example: Hach Model 5-B, 1 to 30 gpg) | Total hardness; for the 5-B, each drop of titrant equals 1 gpg | An exact grains-per-gallon number for sizing; about 100 tests per kit | Hach notes high iron or manganese can turn the sample orange-brown and interfere with the reading |
| Iron color-disc kit (example: Hach IR-18C, 0 to 7 mg/L) | Ferrous (dissolved, "clear-water") iron, in 0.2 mg/L steps | Well owners checking whether iron needs a filter or extra softener capacity | It measures ferrous iron only; total iron needs a separate total-iron test |
| Soap-bottle test | Nothing numeric; few suds suggests hard water | A free first look | Can't size anything |
| TDS meter | Total dissolved solids | Other water questions | Not a hardness test. A salt softener swaps calcium and magnesium for sodium or potassium, so TDS stays about the same before and after |
| State-certified lab | Whatever you order (bacteria, nitrate, lead, iron, hardness) | Well water, home purchases, health questions | Costs more; order the tests you actually need |
On a private well? Test for safety, not just softening
A softener does not make well water safe. The Florida Department of Health strongly recommends private well owners test for bacteria and nitrate at least once a year, and says most homeowners should test for lead every three years. Your county health department can give sampling instructions, and the state says tests usually run $20 to $30 per sample. Hillsborough County well owners can start with the Florida Department of Health in Hillsborough County's water sampling page. Always use a state-certified lab for health tests.
For softening on a well, add hardness, iron (ideally total iron) and manganese to that lab order or test them at home.
How to test so the numbers are useful
- Test raw water from a tap that is not softened (often an outdoor spigot or the line before the softener). That's the number for sizing.
- Test treated water from a cold tap you know runs through the softener to check that an existing system works.
- Test iron right after you fill the sample; Hach's iron kit instructions say to analyze samples immediately.
- Write down the date, the tap, and the units (gpg or mg/L), and bring them to every quote.
Use your results on a quote
- Ask the installer what hardness and iron they used to size the system, and compare it with your own numbers.
- If their in-home test shows much higher hardness than your utility report or kit, ask to see the test and the units.
- Plug your numbers into the sizing guide and check that the tank size fits the valve (see Clack vs Fleck).
Sources
- City of Tampa: 2025 Water Quality Report (hardness 211 mg/L, 12.3 gpg)
- Hillsborough County: Water Quality Reports and system map
- Tampa Bay Water: 2025 Water Quality Report
- USGS: Hardness of Water
- EPA: Secondary Drinking Water Standards
- Hach: Total Hardness Test Kit, Model 5-B
- Hach: Total hardness drop-count test instructions (iron/manganese interference)
- Hach: Iron (Ferrous) Color Disc Test Kit, Model IR-18C
- Hach: IR-18C iron test kit manual
- Rheem Water Treatment: How to test for hard or soft water (TDS is not a hardness test)
- Florida Department of Health: Private Well Water Testing
- Florida Department of Health in Hillsborough County: Water Sampling Forms
Next: size your softener from your test results