About

This is a reference site on Water hardness and water filters for home espresso machines: what hardness means, how to measure it, how scale forms and what the maker says about water, kept deliberately narrow.

Facts on these pages come from published sources, such as makers' documentation, official pages and reference works, and each page links to the ones it used. Every page shows when it was last checked.

There are no ads here, and nothing is for sale.

What you read here is general information. Your own equipment's manual comes first, and where safety or the law calls for a qualified tradesperson, use one.