Cities With the Hardest Water in America (2026 Data Study)
We ranked 86 of the largest U.S. cities by utility-reported water hardness. Madison, Las Vegas and Phoenix are among the hardest; Boston and Portland are the softest.
Plain-English guides to water softeners, water filters and water quality for US homes, based on EPA, USGS and NSF sources.
Featured guides
All guides
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Water Softener Regeneration Cycle: How It Works and How Often
The four stages of a water softener regeneration cycle, how long it takes, how often it should run and how to fix regeneration problems.
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How Does a Water Softener Work? Ion Exchange Explained
How a water softener removes hardness through ion exchange, the parts inside it, how regeneration works and what it can and cannot remove.
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Cloudy Well Water: 6 Causes and How to Fix Each One
Why well water turns cloudy or milky, how to use the glass test to find the cause, and how to fix it.
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UV Water Filter: How UV Purifiers Work for Well Water
How UV water purifiers disinfect well water, what they need to work, how to size one and how to maintain it.
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Sediment Filter for Well Water: Micron Ratings, Types and Sizing
How to choose a sediment filter for well water: types, micron ratings, sizing, installation and replacement.
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Well Water Smells Like Sulfur (Rotten Eggs)? Causes and Fixes
Why well water smells like rotten eggs, how to find the source, and which treatment removes the sulfur smell.
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Coliform Bacteria in Well Water: What It Means and What to Do
What a positive coliform or E. coli test means for your well, what to do right away and how to make the water safe again.
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How to Shock a Well: Step-by-Step Shock Chlorination Guide
When to shock chlorinate a well, how much bleach to use for your well size, and how to do it safely step by step.
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Water Softener for Well Water: How to Choose and Size One
How to choose and size a water softener for well water, including iron-compensated hardness, pump flow and pre-filters.
