Water softeners · buyer guide
Best water hardness test kits: strips vs titration vs digital
You cannot size a softener, set its hardness value, or prove it is working without a usable number in grains per gallon (GPG). Here is how the three common test styles compare, which one we would pick for each job, and how to take a sample that means something.
What you are actually measuring
- Total hardness = calcium + magnesium, usually reported “as CaCO3.” This is the number a softener removes.
- Units: 1 GPG ≈ 17.1 mg/L (ppm) as CaCO3. Softener valves are usually programmed in GPG. See how to size a softener by GPG.
- Calcium hardness alone (common on pool and aquarium tests) under-reads total hardness because it ignores magnesium.
The three test styles compared
| Style | How it works | Best for | Watch-outs |
|---|---|---|---|
| Test strips | Dip a pad, compare color to a chart | Fast yes/no checks on softened water; monthly screens | Coarse color bands; lighting and color vision matter; not precise enough to program a valve |
| Drop-count titration | Add indicator, count titrant drops until the color flips | Sizing, setting the valve, before/after softener diagnostics | Takes a few minutes; follow sample-volume instructions exactly; reagents have a shelf life |
| Digital / colorimeter | Meter reads color intensity of a reagent reaction | Users who want a numeric readout and repeatable results | Many read calcium only or low ranges; still need reagents; a TDS pen is not a hardness meter |
Our picks
Best overall for homeowners: Hach 5-B total hardness titration kit
The Hach Model 5-B (145300) is a drop-count titration kit that Hach rates for roughly 1–30 GPG, with one drop equal to 1 GPG and about 100 tests per kit (per Hach’s listing). It is a long-running Amazon Best Seller in hardness testing equipment, and it is the kit we reference across this site for sizing and diagnostics. Use it on raw water before you buy a softener and again on softened water after install.
Best quick check: WaterWorks total hardness strips
WaterWorks 481108 total hardness strips (30) are individually foil-packed and fast. They are fine for confirming “soft vs not soft” at a softened tap once a month, or after a salt bridge or regeneration problem. They are a screen, not a sizing tool — if a strip says something changed, confirm with titration.
Digital option: read the spec before you buy
Handheld colorimeters can give a cleaner numeric readout than eyeballing a color chart, but many are designed for calcium hardness or for pool and aquarium ranges. If you want a digital meter, confirm it reports total hardness across the range you expect (well water can run well above 20 GPG). Browse digital total-hardness testers on Amazon and check the stated parameter and range. Skip TDS pens for this job — TDS includes sodium and other dissolved solids, so softened water can show similar or even higher TDS than raw water.
How to take a sample that means something
- Raw water: sample from a tap that is upstream of the softener (often an outside hose bib or a tap near the pressure tank) or put the softener in bypass first. Confirm the plumbing — many outside taps are softened.
- Softened water: use a cold tap fed by the softener. Avoid hot water; heaters can change readings.
- Run the tap a minute or two so you are not testing water that sat in the line.
- Use a clean container rinsed with the water you are testing. Follow the kit’s sample volume exactly.
- Use the same method for raw and softened water so the comparison is fair.
- Write down the date, tap, and result. A simple log makes softener problems much easier to diagnose.
What to do with the number
- Sizing: raw GPG (plus an allowance if you have iron) drives the daily grain load — see size by GPG.
- Programming: enter the raw hardness value your valve asks for; see metered vs time-clock regeneration.
- Diagnostics: softened water should read close to zero. If it does not, start with is my softener actually working? and salt bridges.
- Salt-free systems: conditioners and scale-control media do not remove hardness, so a hardness test will read about the same before and after. That is expected — see salt-based vs salt-free.
If your test results conflict, or you are choosing equipment for a well, talk to a licensed water-treatment professional or licensed plumber first. For residential water questions, you can also contact R.E. Merrill & Associates.
Sources
- Hach product listing for Model 5-B (145300) — drop-count titration, 1 drop = 1 GPG, ~1–30 GPG range, ~100 tests.
- Industrial Test Systems WaterWorks 481108 listing — total hardness strips, 30 per pack.
- Hardness unit conversion — 1 GPG ≈ 17.1 mg/L as CaCO3.