Most people first suspect hard water because something looks wrong. Soap won't lather well, the shower glass has a cloudy film, or a faucet has a white crust. Those signs are real, but they are also easy to confuse with other problems, and they don't tell you how hard your water is. Before you get quotes or compare softeners, get a number. The number tells you whether a softener makes sense, how big a unit you may need, and whether a sales pitch matches your actual water.
Start with your utility's water quality report
If you are on city water, your utility is required to publish a water quality report each year, and most post it on their website or mail it with the bill. Look for a hardness figure. It is usually listed in milligrams per liter (mg/L) or grains per gallon (gpg), and it is often stated as calcium carbonate. If you see only mg/L, one grain per gallon is about 17.1 mg/L, so you can convert between the two. Write down the number and the year of the report, since the figure can change over time.
Keep in mind that the report describes the water at the treatment plant or at the point of entry to the system, not necessarily the water at your tap. Pipes, your water heater, and any treatment already in your home can change it. Treat the report as your starting point, not the final answer.
If you are on a private well, test it yourself
A utility report does not cover a private well. Hardness in well water can vary a lot from one property to the next, and it can shift over the years as the aquifer and the well change. For well water, send a sample to a certified lab. Ask for hardness, and ask them to report it in the same units you plan to compare. Many labs will also test for iron and manganese in the same sample, which matters because those minerals can make a water test look like a hardness problem when it is not.
Use a test strip or drop kit at the tap
A home test strip or drop kit is a quick way to check a tap today. Run the cold tap for a minute or two so you are sampling water from the line, not water that has been sitting in the pipe. If you already have a softener or other treatment, test the water before it, at a cold tap that bypasses the unit if you have one, so you measure the raw supply. Read the result against the color chart on the package, and write down which tap you used.
A strip is a rough measure. Use it to confirm the picture from the utility report or the lab, not as the only basis for a purchase. If the strip result and the report disagree sharply, test again and consider a lab sample before you decide.
Read the symptoms as clues, not proof
Symptoms can support the number. Check whether you see white, chalky crust on faucet aerators and showerheads, whether soap or shampoo lathers poorly even after you use more, whether glass and shower doors form a cloudy film that wipes off hard, and whether skin feels tight after showering. None of these prove hard water on their own. Low water pressure, a clogged aerator, sediment, or a different mineral can produce similar marks. If you see rust-colored staining instead of white crust, you are likely looking at iron, and a hardness test alone will not explain it.
Write down what you found before you talk to anyone
Put the report figure, the lab or strip result, the tap you tested, and the symptoms you noticed on one page. This is your record. When you compare companies, you can check whether each installer asks for the same information, whether they test your water on site, and which hardness figure they used to size their recommendation. Ask them to show the test result and the scale they used, and ask them to put the sizing number in writing. If the number they quote does not match the number you collected, ask them why before you go further.
Once you have a clear number and a short list of installers, compare them using the rankings on the Best Water Softener Companies in St. Louis page, and read how each entry was rated on the How We Rate Water Softener Companies page so you know what the scores measure and what they leave out.