Test kits split into three groups that are not substitutes for each other, and buying the wrong group is the usual reason someone ends up with a drawer of test strips and no answer. Work backwards from the decision you are trying to make, and the right group becomes obvious in about a minute.
Strip kits: fast triage
Dip strips read by comparing a color to a chart, covering hardness, chlorine, pH, iron, nitrate and a few others. They are subjective, sensitive to lighting and timing, and coarse, which makes them useless for a health decision and genuinely useful for triage. A hardness strip that puts you clearly in the hard band justifies a softener. A chlorine strip confirms whether a carbon filter is still working. Keep them dry, watch the expiry date, and treat the result as a direction rather than a measurement.
Reagent and titration kits: better numbers, narrow scope
Drop count titration kits, the sort used for hardness and alkalinity, give a much more repeatable figure than a strip because you are counting drops to a color change rather than judging a shade. They are the right tool for sizing a softener, for tracking alkalinity on acidic water, and for anyone who wants to measure the same parameter regularly. They cover only a handful of parameters and require a little care with technique, but within that scope they are genuinely quantitative.
Mail in laboratory kits: the only real answer for health
For bacteria, nitrate, arsenic, lead, metals and volatile organics, the kit is a set of bottles, preservation instructions and a courier label, and the analysis happens at an accredited laboratory with a stated method and detection limit. No consumer gadget substitutes. Choose a package that covers what is plausible in your area rather than the largest available list, and follow the sampling instructions exactly, since holding times and stagnation requirements change results more than most people expect.
Reading the free report first
Before buying any kit, if you are on a community supply, read the utility's annual report. The EPA notes that every community water system publishes a Consumer Confidence Report and maintains a finder for them, and it states hardness, the disinfectant used and the results of required monitoring. That may answer the question at no cost and will tell you what is worth testing at your own tap, which is usually a much shorter list. Our test kit guide covers packages for private wells.
Questions people ask about drinking water test kits
Are test strips good enough?
For hardness and chlorine triage, usually yes. For anything health related they are far too coarse and subjective to base a decision on.
What should I use to size a softener?
A drop count titration hardness kit or a laboratory figure, since a strip is too coarse to specify equipment from.
Can I test for bacteria or lead at home?
Not meaningfully. Those need an accredited laboratory with a stated method and detection limit, using bottles and instructions they supply.
What should I do before buying a kit?
Read your utility's annual Consumer Confidence Report. It states hardness and required monitoring results at no cost and narrows what is worth testing.