How hard is my water?
Put in your ZIP code. You get the hardness for your county, what it means, and whether a softener is worth it.
Typical US county
8.7 gpg
149 mg/L
Classification
Hard
Counties above 120 mg/L
55%
1,718 of 3,110
That is the middle of the 3,110 counties with monitoring data, so it is a rough national picture rather than your water. Put your ZIP code in for the county you actually live in.
What the answer means
Hardness is dissolved calcium and magnesium. It is the reason for scale in a kettle, spots on glassware, and soap that will not lather. It is measured as if it were all calcium carbonate, which is why the same water is quoted as 10 grains per gallon in one place and 171 mg/L in another, and both are correct.
| Class | mg/L | Grains per gallon | Counties | What you notice |
|---|---|---|---|---|
| Soft | 0 to 60 | 0 to 3.5 | 893 | No treatment needed. Soap lathers easily and there is no scale. |
| Moderately hard | 60 to 120 | 3.5 to 7 | 499 | Noticeable but usually tolerable. Some spotting on glassware. |
| Hard | 120 to 180 | 7 to 10.5 | 401 | Scale in kettles and on fixtures, more soap needed, shorter appliance life. |
| Very hard | over 180 | over 10.5 | 1,317 | Persistent scale, water heater efficiency loss, most households soften. |
Source: Water Quality Portal (USGS, EPA and state agencies), waterqualitydata.us, retrieved 2026-09-19. 2,904,346 samples across 3,110 counties.
This is ambient water, not tap water. These figures come from samples taken from wells, streams and springs by USGS, EPA and state agencies. Municipal utilities treat, blend and sometimes soften water before it reaches a tap, so a city supply can be considerably softer than the ground beneath it. Treat this as a good guide for a private well and an approximate one for city water. Your utility's annual water quality report gives the real number for a municipal tap, and a test strip gives it for yours.
What hard water costs you
Hardness is not a health problem. It is a maintenance and running-cost one, and the costs are real enough to be worth the arithmetic. A four-person household on 15 grain water puts about 70.4 pounds of dissolved mineral through its water heater every year.
- Water heaters. Scale on the heat exchanger or tank bottom insulates it, so the burner or element runs longer for the same hot water. A scaled tank heater also fails sooner.
- Soap and detergent. Hardness minerals react with soap before it can lather, so you use more of everything and still get a film left behind.
- Fixtures and glass. The white crust on a shower head and the cloud on glassware are the same calcium carbonate, deposited as water evaporates.
- Hair and skin. The film is soap scum rather than damage, but it is the single most common complaint about hard water. What it does and what actually helps.
The hardest counties in the country
Ranked by the median of all hardness samples recorded in the county.
| County | State | mg/L | gpg | Samples | Class |
|---|---|---|---|---|---|
| Willacy County | Texas | 6,200 | 362.2 | 24 | Very hard |
| Carteret County | North Carolina | 4,800 | 280.4 | 1,437 | Very hard |
| Childress County | Texas | 4,800 | 280.4 | 533 | Very hard |
| Bristol County | Rhode Island | 4,650 | 271.6 | 6 | Very hard |
| King County | Texas | 4,290 | 250.6 | 1,421 | Very hard |
| McIntosh County | Georgia | 3,700 | 216.1 | 458 | Very hard |
| Crockett County | Texas | 3,580 | 209.1 | 9 | Very hard |
| Hardeman County | Texas | 3,100 | 181.1 | 95 | Very hard |
| Pecos County | Texas | 2,900 | 169.4 | 397 | Very hard |
| Cottle County | Texas | 2,800 | 163.6 | 884 | Very hard |
| Foard County | Texas | 2,700 | 157.7 | 301 | Very hard |
| Hall County | Texas | 2,500 | 146 | 404 | Very hard |
| Knox County | Texas | 2,470 | 144.3 | 1,155 | Very hard |
| Ward County | Texas | 2,460 | 143.7 | 5 | Very hard |
| Kent County | Texas | 2,400 | 140.2 | 361 | Very hard |
| Howard County | Texas | 2,340 | 136.7 | 106 | Very hard |
| Reeves County | Texas | 2,300 | 134.4 | 453 | Very hard |
| Harmon County | Oklahoma | 2,200 | 128.5 | 778 | Very hard |
| Newport County | Rhode Island | 2,182 | 127.5 | 8 | Very hard |
| Stonewall County | Texas | 2,130 | 124.4 | 2,773 | Very hard |
| Fisher County | Texas | 2,100 | 122.7 | 37 | Very hard |
| Rosebud County | Montana | 2,090 | 122.1 | 16,390 | Very hard |
| Hudson County | New Jersey | 2,000 | 116.8 | 60 | Very hard |
| Dickens County | Texas | 2,000 | 116.8 | 12 | Very hard |
| Kenedy County | Texas | 2,000 | 116.8 | 131 | Very hard |
And the softest
| County | State | mg/L | gpg | Samples | Class |
|---|---|---|---|---|---|
| Scott County | Kansas | 1 | 0.1 | 1,198 | Soft |
| Hancock County | Mississippi | 1 | 0.1 | 365 | Soft |
| Wilkinson County | Mississippi | 1 | 0.1 | 169 | Soft |
| Floyd County | Indiana | 2 | 0.1 | 12 | Soft |
| Crawford County | Kansas | 2 | 0.1 | 1,772 | Soft |
| Perry County | Mississippi | 2 | 0.1 | 588 | Soft |
| Franklin city | Virginia | 3 | 0.2 | 8 | Soft |
| Tuolumne County | California | 3 | 0.2 | 410 | Soft |
| Towns County | Georgia | 4 | 0.2 | 451 | Soft |
| Bennington County | Vermont | 4 | 0.2 | 964 | Soft |
| Fannin County | Georgia | 5 | 0.3 | 719 | Soft |
| Lumpkin County | Georgia | 5 | 0.3 | 984 | Soft |
| Marion County | Georgia | 5 | 0.3 | 62 | Soft |
| Rabun County | Georgia | 5 | 0.3 | 848 | Soft |
| Taylor County | Georgia | 5 | 0.3 | 288 | Soft |
| Harrison County | Mississippi | 5 | 0.3 | 577 | Soft |
| Hamilton County | New York | 5 | 0.3 | 2,766 | Soft |
| Transylvania County | North Carolina | 5 | 0.3 | 875 | Soft |
| Aiken County | South Carolina | 5 | 0.3 | 844 | Soft |
| Lee County | South Carolina | 5 | 0.3 | 278 | Soft |
| Oconee County | South Carolina | 5 | 0.3 | 1,364 | Soft |
| Windham County | Vermont | 5 | 0.3 | 1,047 | Soft |
| Dawson County | Georgia | 6 | 0.4 | 245 | Soft |
| Peach County | Georgia | 6 | 0.4 | 21 | Soft |
| Schley County | Georgia | 6 | 0.4 | 25 | Soft |
Frequently asked questions
How do I find out how hard my water is?
Put your ZIP code in the box at the top of this page. It resolves the ZIP to its county and gives you the median of every hardness sample recorded there, which is 2,904,346 samples across 3,110 counties in total. That figure is ambient water, so for a private well it is a good guide and for a treated municipal supply it reads high. The two more accurate answers are your utility's annual water quality report, which is published free and by law, and a test strip in your own tap, which costs a few dollars and is the only measurement of your actual water.
What is considered hard water in grains per gallon?
Above 7 grains per gallon is hard, and above 10.5 grains per gallon is very hard. Below 3.5 grains is soft and needs nothing. Those are the US Geological Survey bands, converted from their mg/L thresholds of 60, 120 and 180 at 17.118 mg/L per grain. Water treatment in the United States is sold in grains; laboratory and utility reports are almost always in mg/L.
Is hard water bad for you?
No. Hardness is calcium and magnesium, both of which are dietary minerals, and no drinking water standard limits it as a health contaminant. The US EPA classes it as a secondary, aesthetic characteristic. What hard water damages is plumbing and appliances, not people. Separately, hardness tells you nothing about lead, PFAS, nitrate or bacteria, which are health questions and are answered by a laboratory test, not by a hardness figure.
Is hard water safe to drink?
Yes. There is no upper limit on hardness in drinking water anywhere in US regulation, and water at 500 mg/L is unpleasant to wash in long before it is a problem to drink. Some studies find a small protective association between hard water and cardiovascular outcomes, and none find harm. It tastes mineral, which some people prefer and some do not.
What size water softener do I need?
Multiply the people in the house by about 75 gallons a day, multiply by your hardness in grains per gallon, and that is the grains the softener has to remove every day. Multiply by the days you want between regenerations, usually 7, and buy the nearest size up. A four-person household on 15 grain water needs about 31,500 grains of capacity, which is a 32,000 grain unit. The sizing calculator does it with the iron and salt-setting corrections.
What is the difference between grains per gallon and ppm?
One grain per gallon equals 17.118 mg/L, and mg/L and ppm are the same number for water. So 10 grains per gallon is 171 ppm. The confusion is worth money: a softener salesman quoting "you are at 250" means mg/L, which is about 14.6 grains, and a unit sized as though 250 were grains would be four times too big.
Does hard water cause hair loss?
No. There is no evidence that hardness causes hair to fall out. What it does is leave a film of soap scum and mineral deposit on the hair shaft, which makes hair feel rough, look dull and tangle more, and that extra mechanical breakage is what people notice. A chelating or clarifying shampoo removes the film, and a shower filter reduces it. The detail.
Do water hardness test strips work?
Well enough for this decision. A dip strip reads in bands rather than to the nearest grain, which is all you need to choose a softener size, and it costs a few dollars for a pack. Read it in daylight at the time the instructions say, because the pad keeps developing. For a figure precise enough to argue with a water treatment quote, use a titration kit or your utility report.