Is your water hard? Start with a measurement
Chalky deposits and soap residue can prompt a useful question: how hard is your water? Before buying a filter or softener, find a measurement that answers that question directly.
What hardness means
Water hardness mainly reflects dissolved calcium and magnesium. Those minerals are different from the disinfectants used by a water supplier. A device intended to reduce chlorine is not automatically a device that reduces hardness.
Ask your water supplier
Check the supplier’s water report or ask for a local hardness result. Record the units and the area covered by the report. A result for a broad service area may differ from the water at your tap, especially if the supply changes or a building has its own treatment system.
Use a hardness-specific kit
Choose a kit that explicitly measures hardness, and follow its sampling, timing and reading instructions. Record the number and units rather than only a colour description.
- Note whether the result is reported as mg/L or ppm as calcium carbonate, or in another unit.
- Test the water you actually want to treat.
- Repeat a surprising result; use an appropriate laboratory when accuracy or a separate contamination concern matters.
A general total dissolved solids (TDS) meter measures a broader property. Its number alone cannot identify how much calcium and magnesium is present.
Choose treatment after testing
Conventional ion-exchange softeners reduce hardness by exchanging calcium and magnesium for other ions. Their suitability depends on household needs, plumbing, maintenance and local conditions. Ordinary shower filters should not be assumed to perform this job.
Hardness is also not a complete water-safety test. If you have a private well or suspect contamination, seek advice about the specific tests needed rather than relying on a hardness result.
Keep a simple record
Write down the sample location, date, kit or laboratory, result and units. That makes it easier to compare quotes and check any later treatment results.
Sources and limits
USGS: water hardness and dissolved minerals
USGS: water terminology and hardness units
This guide explains household decision-making. It does not establish the safety of a particular water supply.