Hardness is one of the few water parameters a household can measure meaningfully at home, and there are three ways to do it with very different precision. Choosing the right one depends entirely on what the number is for: satisfying curiosity, sizing a softener, or settling a disagreement with a supplier.
Strips, for a band
A hardness strip is dipped and read against a colour chart in seconds. It is subjective, sensitive to lighting and to how long the strip is held, and it places you in a band rather than giving a figure. That is enough to answer whether you have a hardness problem at all, which for many households is the whole question. 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, for a figure you can size from
A drop count kit gives a repeatable number, because you count drops of reagent added to a measured sample until the colour changes, and each drop corresponds to a defined amount of hardness. The count is the measurement, so it does not depend on judging a shade. These kits cost little, take a few minutes, and are accurate enough to size a softener from, which strips are not. This is the method to use before buying equipment or when comparing treated and untreated water.
Laboratory analysis, for certainty
A laboratory reports hardness as part of a wider panel with a stated method and detection limit, which matters when the figure is contested, when it forms part of a specification someone else will act on, or when you are testing several parameters anyway. On a private well it usually makes sense to get hardness alongside iron, manganese and pH, since those interact and specifying treatment from one of them alone is a common error.
Reading the result
The USGS classifies hardness as dissolved calcium and magnesium, with soft at 0 to 60 mg/L as calcium carbonate, moderately hard at 61 to 120, hard at 121 to 180 and very hard above 180, while much of the trade uses grains per gallon, whose figures are far smaller. Always confirm the unit before comparing to a chart or a sizing table. On a community supply the utility publishes the figure at no cost. Our hardness testing guide covers local services.
Questions people ask about water hardness testing
Are hardness strips accurate enough?
They place you in a band, which answers whether you have a problem. For sizing equipment, use a titration kit or a laboratory figure.
How does a titration kit work?
You count drops of reagent added to a measured sample until the colour changes, and the count is the measurement.
When is a laboratory worth it?
When the figure is contested, forms part of a specification, or when you are testing iron, manganese and pH at the same time.
Why do published hardness figures differ so much?
Two units are in use: milligrams per litre as calcium carbonate, and grains per gallon. Check which one a figure uses.