How to test water hardness at home
Start with the task you want to complete: setting an appliance, checking a softener, or understanding a water-quality concern.
Find the published area result
Use your supplier’s postcode checker and look for total hardness expressed as calcium carbonate. Note the reporting period. A supply-area summary is useful context, but is not a test of the water at your tap.
Choose a hardness test, not a general score
For a home hardness kit, check that it measures total hardness, that its range includes the value you expect, and that its instructions state the units. Follow the kit’s sampling, timing and reading instructions exactly. Record the date, tap, result and unit. A hardness-only result cannot answer questions about lead, bacteria or overall drinking-water quality.
Use the result for your appliance
Match the unit to your appliance manual before choosing a setting. If the reading falls close to a setting boundary or differs greatly from the supplier report, repeat the measurement according to the kit instructions and contact the supplier or appliance manufacturer for help.
Check your published area information
Sources and review
Sources checked 6 September 2026. Prepared by WaterGrade.
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