Best Water Hardness Test Kit (2026): Strips vs Drops vs Certified Lab
Number copied. Text it from your phone: 443-277-2204.
The best water hardness test kit is the one that fits what you'll do with the number. A hardware-store strip, about $13 for a bottle, tells you soft or hard. A drop kit counts the grains one drop at a time, which is enough to set a softener. To size and buy a softener, use a certified lab test: our $99 kit reports your hardness in mg/L and grains per gallon. On a well, test iron and pH along with hardness.
Caller "If I just ended up getting the quick hardness meter, um, you know, the strips kind of thing..."
Aidan "That's fine."
A well owner in Rhode Island asked me that in October, before choosing a PFAS filter. The question was whether iron and hardness were low before the filter went in, and a home test kit answers that. This page is which hardness test fits which decision.
Quick Answer
Hardness is the calcium and magnesium in your water. A strip tells you if it is hard. A drop kit counts it in grains per gallon. A certified lab measures it and reports grains per gallon and mg/L (the same as ppm).
- Strips, about $13. Dip one and match the color. Four companies mail one free. See free hardness test strips.
- Drop kit, about $52. Each drop is one grain of hardness. See the three kinds compared.
- Certified lab, $99. A lab measures your hardness. See our pick.
- Which to use. Curious? A strip. Checking a softener? A strip. Setting a softener? A drop kit. Buying a softener? A lab test, and on a well the $199 well test. See well water.
We don't carry strips or drop kits. Our lab tests are the $99 hardness test, the $199 city water test and the $199 well water test.
What's in This Guide
Mid Atlantic Water Hardness Test Kit ($99, Certified Lab)
If you are sizing a water softener or making any buying decision, a certified lab hardness test is the right tool. Your sample goes to an independent certified lab in the SimpleLab network and the report gives your hardness as calcium carbonate in both mg/L and grains per gallon. Softeners are sized in grains per gallon.
A lab number matters most near the line. Of the four hardness kit results our customers have had since May, three came back between 7.4 and 8.2 grains (127 to 140 mg/L), right at the 7-grain line where I recommend a softener. A strip can't place you that closely: on Hach's strip chart, 120 and 250 ppm are neighboring colors, so anything from about 7 to 15 grains falls between them. The fourth kit came back with almost no hardness (under 0.21 mg/L), so that house needs no softener.
Order the kit, take the sample, and mail it back with the prepaid label. The lab takes about 5 business days once it has the sample; counting the mail both ways, those four took 12 to 19 days from the order. Not sure what your numbers mean once they arrive? That is the point of the expert review.
Three kinds of hardness test compared
A strip shows a color, a drop kit counts grains, and a lab measures the number. Each is the right tool for a different job.
| Test strip | Drop kit | Certified lab | |
|---|---|---|---|
| Example | Varify, 150 strips | Clean Water Store Pro II, or Hach 5-B | Our water hardness test kit |
| Price | About $13 for the bottle | $52 for 30 to 50 tests (Clean Water Store) | $99 per test |
| How you use it | Dip it, then match the color to the chart on the bottle | Add drops to a water sample until it turns blue, and count them | Mail a water sample to the lab |
| What you learn | A color range, on a chart from 0 to 425 ppm | Each drop is one grain per gallon | Hardness in grains per gallon and mg/L |
| Highest it reads | 425 ppm, about 25 grains | Up to 30 grains on the Hach 5-B | Our customers' well tests reached 103 grains |
| Best for | Finding out if your water is hard, and checking a softener | Setting a softener | Sizing and buying a softener |
The line that matters is 7 grains per gallon (120 mg/L). At 7 grains and above, I recommend a water softener. To turn mg/L into grains, divide by 17.1. The water hardness scale has the full bands.
When a hardware-store strip is enough
A strip is enough when all you need to know is soft or hard. If it reads soft, you're done. It's the first thing I say in my video: the fastest way to test for hardness is a kit from Lowe's, Home Depot or Amazon. Strips are fairly accurate and give you a good idea of what the issue is.
That's what I told the Rhode Island caller at the top of this page: get a home test kit for iron, hardness and pH at Lowe's or Home Depot, and make sure they're low or nonexistent. I think an all-in-one kit there is about $25. A strip is also all you need to check a working softener; the FAQ below covers how.
Where a strip stops: if it reads hard, get a number before you buy anything. The top color on a strip chart is 425 ppm, about 25 grains, so a strip can't tell 25 grains from anything higher. A caller in Wisconsin, with a 40-year-old iron filter and softener, had strips that showed "extremely high hardness." I said a lab is the most accurate way to get the real numbers.
Free hardness test strips
Four companies mail a free hardness strip: Morton, EcoPure, Whirlpool and Rheem. All four sell water softeners or softener salt. A free strip is still a strip: it tells you soft or hard.
| Company | What they mail | What their page says |
|---|---|---|
| Morton Salt | One test strip. The form asks for your email and street address. | Morton sells water softener salt. |
| EcoPure | One strip, U.S. and Canada only | Says "If your number is 7 or higher, you need an EcoPure Water Softener!" |
| Whirlpool | One strip within 14 days, U.S. and Canada only | Next step: "Find your softening solution." The form has a sign-up for special offers. |
| Rheem | One strip within 14 days, U.S. and Canada only | Says the right softener model "depends on the hardness level." |
| Discount Water Softeners | A free hardness test kit, mailed from Illinois | Says its free kit "alone will not be sufficient" to size a softener. Sells a well test kit with a $25 credit toward a Genesis softener system. |
None of that makes the strip wrong. It means the strip comes from a company that sells softeners or salt, and what it gives you is a color step, not a number to size from. Discount Water Softeners says so itself: they want your iron, pH and hardness before they size a softener.
A free in-home test from a dealer is a different thing, because a salesperson brings the kit to your house. The test kits we use in this industry are pretty accurate: not as accurate as an independent lab, but close. There are also some shady characters who will manipulate the in-home test to get the results they want so they can sell you equipment. One caller's Culligan test showed 12 ppm iron, and the caller was told, "Well, the only way we can treat it is with a water softener." Another, on a Delaware well where pH was the only problem, was pitched a backwashing neutralizer or a feed you add potash to. What a well water test costs covers what a dealer's free test checks, and is my water treatment quote too high covers the quote that follows it.
Well owners should test more than hardness
On a well, test for iron, manganese and pH too. They change which equipment goes in, and in what order. I told the Rhode Island caller that before a PFAS filter, iron or extremely hard water has to come out first. Hach adds that high levels of iron or manganese can foul the resin in a softener.
Very high iron can also get in the way of the hardness test itself. Hach says its HA-71A drop kit "works best for natural water samples, especially when iron or manganese is present." A caller in North Carolina with very high iron had a tester come out who couldn't get an accurate hardness reading. With that much iron, the sample has to be diluted and retested, and the lab is the best way to do it.
Hard water was also more common on wells than on city water in what my customers sent in. Of 402 well tests my customers sent in since May, 44% came back at 7 grains or more, and 21 came back at 25 grains or more, at or past the top of a strip's chart. The highest was 103 grains. On city water it was 35% of 51 tests, and none was over 23 grains.
So on a well I'd skip the $99 hardness kit and get the well water test kit ($199). It covers 53 contaminants and water-chemistry values, including hardness, iron, manganese and pH, and results usually take 2 to 4 weeks from the order. On city water, the $99 kit answers the hardness question; the city water test kit ($199) covers 47 contaminants, including lead and copper. Once you have the number, water softener sizing turns your grains and household size into a softener size.
Send me your hardness number
Text a photo of your strip or report to 443-277-2204 and Aidan will read it and tell you what it means. Tell me how many people live in the house.
8 AM to 5 PM Eastern, seven days a week. A real person, not a call center.Frequently asked questions
Are water hardness test strips accurate?
Strips are accurate enough to tell soft from hard, but not accurate enough to size equipment. Use a strip to check. Use a lab test before you buy.
How do I test my water softener?
Test a tap after the softener with a hardness strip. Softened water should read zero hardness. A caller with 6.44 grains asked me what the softener brings it down to; the answer is zero, which is what you want. If it reads hard, start with water softener troubleshooting.
What should a water softener be set at?
Set it about 4 grains above your raw water hardness. Raw water is the water coming into the house, before the softener. So if your raw water is 6 grains, set it at 10. On the Fleck valve, the hardness comes set at 20, so change it. You also set the capacity (the size you bought) and the time of day; Fleck 5600SXT programming walks through it.
Why is EDTA used to determine hardness of water?
EDTA is the liquid you add, a drop at a time, in a drop kit. The sample has a color indicator in it, and you keep adding drops until the color changes. Hach says the drop count is proportional to the hardness. On its 5-B kit, one drop is 1 grain per gallon.
Can hard water damage appliances?
Yes. Hard water leaves scale in water heaters, tankless heaters and dishwashers. The biggest mistake I see is people who test, find hard water and ignore it. Then they're replacing water heaters, dishwashers and washing machines. Hard water vs soft water goes through the signs.
Aidan Walsh
Co-owner & Residential Water Treatment Specialist, Mid Atlantic WaterAidan Walsh has spent 32 years in residential water treatment, the first stretch of it installing and servicing well systems before Mid Atlantic Water became an online supplier. Mid Atlantic Water is a family company; every recommendation on this site is based on what actually failed in the field and what fixed it. If you have a question this page did not answer, call 800-460-5810 or text him at 443-277-2204.
Aidan answers calls and texts 8 AM to 5 PM Eastern, every day.Number copied. Text it from your phone: 443-277-2204.