Household signs point at hardness; a test measures it. If you have got as far as wanting a number, three routes give you one, and they differ in accuracy, cost and what you can do with the result. The one thing that catches everybody is units, because hardness is reported in two different scales and the figures look nothing alike.
Test strips: quick and coarse
A hardness strip is dipped and read against a color chart in seconds. It is subjective, sensitive to lighting and to holding the strip too long, and it places you in a band rather than giving a figure. That is genuinely enough to answer the question being asked here: it will tell you clearly whether you are in the soft end or the hard end. Keep strips dry and in date, read them in daylight, and treat a borderline result as a reason to use a better method rather than as a number.
Titration kits: a real figure at home
A drop count kit gives a repeatable number because you are counting drops of reagent added to a measured sample until the color changes, rather than judging a shade. Each drop corresponds to a defined amount of hardness, so the count is the measurement. These kits cost little, take a few minutes, and are accurate enough to size a softener from, which strips are not. They are the right tool if you are about to buy equipment or want to compare treated and untreated water.
The units that confuse everybody
The USGS reports hardness as milligrams per litre as calcium carbonate, classifying soft at 0 to 60, moderately hard at 61 to 120, hard at 121 to 180 and very hard above 180. Much of the water treatment trade uses grains per gallon instead, and the numbers are far smaller, so a figure that looks low may not be. Always check which unit a result is in before comparing it with a chart or with equipment sizing tables, since mixing the two is the most common misreading.
The free result you may already have
If you are on a community supply, the utility publishes hardness in its annual water quality report, and that figure is specific to your system rather than a regional average. It costs nothing and often makes testing unnecessary. Test your own tap if you are on a private well, if the report and the evidence disagree, or if you are sizing equipment and want to confirm. Our hard water shower head guide covers what to do once you have the answer.
Questions people ask about how can i tell if i have hard water
Are hardness test strips accurate enough?
They place you in a band, which answers the basic question. For sizing equipment, a drop count titration kit or a laboratory figure is better.
Why do hardness figures look so different between sources?
Two units are in use: milligrams per litre as calcium carbonate, and grains per gallon. Check which one a result uses before comparing.
What counts as hard?
On the USGS scale, 121 to 180 as calcium carbonate is hard and above 180 is very hard, with 61 to 120 moderately hard.
Do I need to test at all?
Not if you are on a community supply, where the utility publishes the figure for your system in its annual report at no cost.