HardWaterLab

Guides

HardWaterLab guides

Hard water questions answered with the same chemistry the calculators use.

How to test water hardness at home

Dip a hardness test strip in cold tap water for a second and match the pad to the colour chart: that gives a reading in ppm or gpg within one colour band. For a number accurate enough to size a softener, use a drop-count titration kit, where each drop usually equals 1 gpg. Your water utility’s annual report and the ZIP lookup give the figure without testing at all.

Is hard water bad for you?

No, not to drink. Hardness is dissolved calcium and magnesium, and the World Health Organization has found no convincing evidence that it harms health; both are nutrients. Its real costs are scale, dry skin and dull hair. If you soften it, each grain per gallon removed adds about 7.9 mg of sodium per litre, which matters for anyone on a low-sodium diet.

Do hard water shower filters work?

Mostly no, not for hardness. Shower filters use carbon, KDF or vitamin C, which take out chlorine but not calcium and magnesium. Removing hardness needs ion exchange resin, and one person’s daily 10 minute shower in 15 gpg water carries 315 grains, more than a whole cup of resin can hold. Only a whole-house softener has the capacity.

Frequently asked questions

How do I test my water hardness at home?
Dip a hardness test strip in cold tap water for a second and match the pad to the colour chart: that gives a reading in ppm or gpg within one colour band. For a number accurate enough to size a softener, use a drop-count titration kit, where each drop usually equals 1 gpg. Your water utility’s annual report and the ZIP lookup give the figure without testing at all.
Is hard water bad for your health?
No, not to drink. Hardness is dissolved calcium and magnesium, and the World Health Organization has found no convincing evidence that it harms health; both are nutrients. Its real costs are scale, dry skin and dull hair. If you soften it, each grain per gallon removed adds about 7.9 mg of sodium per litre, which matters for anyone on a low-sodium diet.
Do hard water shower filters actually work?
Mostly no, not for hardness. Shower filters use carbon, KDF or vitamin C, which take out chlorine but not calcium and magnesium. Removing hardness needs ion exchange resin, and one person’s daily 10 minute shower in 15 gpg water carries 315 grains, more than a whole cup of resin can hold. Only a whole-house softener has the capacity.

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