Quick Answer: For a number you can actually program into a softener, get a drop-count titration kit. The Hach 5-B reads total hardness in 1 gpg steps and gives about 100 tests. If you need to confirm your softener is producing truly soft water, you want a low-range titrator such as LaMotte's 3037-DR-01, which resolves down to 0.2 ppm but is sold mainly through lab and water-treatment suppliers rather than Amazon. Strips like ITS WaterWorks 481108 are fine for a quick yes/no, not for setting a softener.
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Most hardness kits fail people for one reason: they answer a different question than the one you asked. A color strip can tell you "your water is hard." It can't reliably tell you whether it's 14 grains or 19, and that difference changes how often your softener regenerates and how much salt you burn. It also can't tell you whether your softened water is at zero or quietly letting 2 grains through.
So pick the kit by the job. There are really only three.
In this guide
- Job 1: "What number do I enter into my softener?"
- Job 2: "Is my softener actually working?"
- Job 3: "Is my water hard at all?"
- Turning any result into a softener setting
- When your kit and the water report disagree
- The dishwasher and other "hardness dial" appliances
- Keeping reagents honest
- A few testing habits that make any kit more accurate
- What we'd actually buy
Job 1: "What number do I enter into my softener?"
This is the most common reason people buy a kit. The softener's control valve wants hardness in grains per gallon (gpg), and you want that number within a grain or so of the truth.
The answer is a drop-count titration kit. You fill a tube to a line, add a buffer and an indicator that turns the water pink or red, then add titrant one drop at a time until it flips to blue. Each drop is a fixed amount of hardness. Count the drops and you have your number. No guessing between two shades of purple.
Hach Total Hardness Test Kit, Model 5-B: best overall
The Hach 5-B is the kit water-treatment pros keep in the truck, and it's the one we'd send most homeowners to. Hach lists it as an EDTA drop-count titration with a red-to-blue endpoint, measuring 1 to 30 gpg in 1 gpg per drop (about 17.1 mg/L as calcium carbonate). It gives roughly 100 tests per kit.
The 30 gpg ceiling covers the vast majority of US homes. If you're on a very hard well and you hit 30 drops without a color change, use half as much sample water and double the result.
- Best for: Programming a softener, checking raw water seasonally, comparing before/after.
- Not for: Proving your softened water is at zero. At 1 gpg per drop, it can't show the difference between 0 and "less than 1."
- Heads-up: The reagents have a shelf life. If your kit sits in a hot garage for three years, replace them before relying on a reading.
LaMotte PHT-DC-LI Total Hardness Dropper Kit: runner-up titration kit
LaMotte is the other long-standing name in field test kits. The 4482-LI-02 is the same basic drop-count idea: one drop equals 10 ppm or 1 gpg as CaCO3, depending on which sample size you use, with a liquid indicator. That dual setup is handy if your water report gives hardness in ppm (mg/L) and your softener wants gpg. You can read either one without converting.
- Best for: Anyone who'd like to read ppm directly, or who wants a second kit for a rental property or a parent's house.
- Downside: Hach's 5-B is easier to find advice about, since half the softener forums reference it. That matters if you're a first-timer looking for help reading the endpoint.
Job 2: "Is my softener actually working?"
This is where most kits fall short. A healthy softener should put out water at or very near 0 gpg. Hardness leaking through at 1 to 3 gpg points to worn seals, a bypass that isn't fully closed, or resin that's tired. A 1-gpg-per-drop kit will often read that as "0 to 1 drop" and tell you everything is fine.
What you want for this job is a low-range kit. LaMotte's 3037-DR-01 is the classic example: LaMotte lists it as a direct-reading titrator with a 0–10 ppm range and 0.2 ppm sensitivity, read off a calibrated syringe instead of by counting drops. That's fine enough to see 1 gpg (about 17 ppm) clearly and to spot the slow creep of hardness that shows up before a softener fails outright. We couldn't find it in stock on Amazon when we checked, so look for it at lab and water-treatment suppliers.
- How to use one: pair it with a regular kit. Use the Hach or the LaMotte dropper on raw water and the low-range kit on softened water only. Raw hard water will blow past a 10 ppm top of range immediately.
- Tip: Test from the softener's outlet or the nearest tap, not from a faucet that might be piped around the softener. Outdoor spigots and kitchen cold lines are often bypassed on purpose.
If your results swing from tap to tap, why hardness tests differ between faucets explains the plumbing reasons. And if the low-range kit shows hardness getting through, start with water still hard after installing a softener.
Job 3: "Is my water hard at all?"
Maybe you've just moved, you're deciding whether a softener is even worth considering, or you want to set a dishwasher's hardness dial. Strips are fine here. They're fast and cheap per test, and they give a range rather than a precise number.
Industrial Test Systems WaterWorks 481108 Total Hardness Strips: best test strips
ITS makes a lot of the strips sold under other names, and the WaterWorks hardness strip is its own flagship. The listing describes a 3-second test, a 0–1000 ppm range, and 50 tests per bottle. The manufacturer's color chart for this line steps through 0, 40, 80, 120, 180, 250, 425 and 1000 ppm. For context, 120 ppm is about 7 gpg and 180 ppm is about 10.5 gpg.
- Best for: A quick check at several taps, or confirming "yes, this is hard water" before you research softeners.
- The limitation: Look at those steps. Between 180 and 250 ppm is a 4-grain gap. That's too coarse to program a softener well.
- Who should skip it: Anyone who already knows the water is hard and needs a number. Buy a titration kit instead.
Varify Water Hardness Test Strips: best for a quick first look
Varify's strips are aimed squarely at households: well or city water, softener and dishwasher settings, a simple color card. They do the same basic job as the ITS strips, so pick whichever is easier to get. As with any strip, read it under daylight or a white LED, at the time the instructions say. Color drifts if you wait.
- Best for: A first look, or splitting a bottle across family members' homes.
- Downside: Same as every strip. A range, not a number. Don't use these to decide whether your softener is leaking a grain or two.
Turning any result into a softener setting
Kits report in different units, and mixing them up is the number-one setup error we see.
- 1 gpg = 17.1 ppm (mg/L as CaCO3).
- Strip reads 250 ppm → 250 ÷ 17.1 ≈ 14.6 gpg.
- Hach 5-B takes 18 drops → 18 gpg directly.
Then adjust for the extras. If you have dissolved iron, most softener manuals tell you to add a few grains of "compensated hardness" for every ppm of iron. Check the multiplier your valve's manual uses. A worked example: 18 gpg hardness plus 1 ppm iron, using a common multiplier of 4, gives a setting of 22 gpg. The full walkthrough is in how to set hardness on a water softener, and our gpg vs. ppm explainer covers the unit conversions if your city's water report uses mg/L or "degrees."
When your kit and the water report disagree
City water reports often list hardness as an annual average, sometimes from several sources blended together. If your utility switches between groundwater and surface water by season, your tap can run several grains above or below the published figure for months at a time. Your own titration is the better number to program into a softener. Recheck it in a different season, and if the two readings differ, set the softener for the higher one.
Wells are the opposite problem: no report at all. A first lab test gives you the full picture (hardness, iron, manganese, pH), and a titration kit lets you keep an eye on hardness between lab tests.
The dishwasher and other "hardness dial" appliances
Many dishwashers and some espresso machines and steam ovens have a water-hardness setting. A strip is usually precise enough for those, since the dial typically has a handful of broad steps. Two notes:
- If you have a softener, set the dishwasher for your softened water, not your raw water. Otherwise the dishwasher's own softening will overcompensate.
- Some European dishwashers use German degrees (°dH) instead of gpg. 1 °dH is about 17.8 ppm, so close to 1 gpg but not identical. Check the manual's table.
Keeping reagents honest
Titration reagents don't last forever. Store kits indoors, out of sunlight, with the caps tightly closed. If a test that used to give a crisp color change starts fading slowly from red to purple to blue, the indicator may be aging. A quick sanity check: test distilled water, which should read zero, and a known-hard water sample. If either looks off, replace the reagents before trusting the kit for softener setup.
A few testing habits that make any kit more accurate
- Run the cold tap for a minute first so you're testing water from the main, not water that sat in the pipe.
- Test cold water. Hot water from a tank can read differently because scale drops out in the heater.
- Use the exact sample volume. With drop-count kits, an overfilled tube is the most common reason two tests disagree.
- Test raw water a few times a year if you're on a well. Hardness can shift with seasons and water table changes.
For a full step-by-step, see how to test water hardness at home.
What we'd actually buy
Most softener owners: the Hach 5-B for raw water, plus a low-range kit like LaMotte's 3037-DR-01 from a lab supplier if you ever need to troubleshoot. Between them you can set the softener correctly and prove it's working. If you're still deciding whether you need a softener at all, a bottle of strips is enough to start.