Guides

How often to descale a coffee machine at each hardness level, in mg/L and gpg, with examples from US and German cities. Your manual overrides our table.

Which dishwasher salt level to choose for your tap water hardness, with a mg/L and gpg table, city examples and what to check in your manual.

Hard water leaves minerals on hair, but one small study found no visible structural damage. What the evidence says, and how to check your own hardness.

Does hard water affect skin or eczema? Studies show an association in children, but softeners have not been shown to treat eczema. Evidence explained.

What a tenant can do about hard water without altering the plumbing, and when a landlord's permission is needed. Real city figures in mg/L and gpg.

How limescale forms in tank and tankless water heaters, which hardness levels matter, and what it costs to ignore it. Real figures for US and UK cities.

What a US Consumer Confidence Report contains, how to read its tables, and why hardness is often missing. Includes where to find your hardness figure.

How to descale an electric kettle: the manufacturer's descaler first, white vinegar second. Steps, rinsing, frequency by hardness, and real city figures.

An ion-exchange softener adds about 0.46 mg of sodium per mg/L of hardness removed. See the arithmetic, city examples and low-sodium options.

A softener removes hardness. Conditioners and inhibitors only change how scale forms. Here is how to choose by your water's hardness, with city examples.