Three steps to better water
Find out
Step 1: Find Out What's in Your Water
Start with your utility's report or a test, not with a filter: the right fix depends entirely on what is actually in your water.
Fix it
Step 2: Choose a Filter or Softener That Fixes It
Match the treatment to the problem, then check the certification listing before you buy: a claim on the box is not a certificate.
Keep it working
Step 3: Keep Your System Working
Cartridge changes, softener salt, sanitizing and retesting: a filter past its rated capacity can stop doing its job.
Latest guides
All filter guidesReverse Osmosis
Best Reverse Osmosis Systems, Checked Against Their Certifications
We checked six popular home RO systems against their NSF, WQA and IAPMO listings: what each is certified for, filter costs, wastewater and who it suits.
Reverse Osmosis
How Reverse Osmosis Works: What It Removes and What It Wastes
How a home reverse osmosis system works, what it removes and misses, how much water goes down the drain, and how to tell if you need one.
Water Softeners
Hard Water: What It Does (and Doesn't Do) and How to Fix It
Hard water is calcium and magnesium, not a health hazard. What it does to pipes, skin and hair, how to test it, and when a softener is worth it.
Water Testing
How to Read Your Water Quality Report (CCR), Step by Step
What MCL, MCLG, action level and range mean in your utility's water quality report, when it arrives, what changes in 2027 and what it can't tell you.
Well Water
Well Water Testing: What to Test For and How Often
Nobody tests a private well but you. What to test every year, what to add for your area, when to test again, how to sample, and how to read the results.
What's in Your Water
Lead in Drinking Water: Sources, Testing and Filters That Work
Where lead in tap water comes from, what the 2024 lead rule changes, how to check your service line and test, and how to pick a filter certified for lead.
Strong evidence
Browse by topic
What's in Your Water
Lead, PFAS, chlorine, hardness, nitrates and more: what each one is, how common it is, what the legal limits are and what the health research says.
Water Testing
Reading your utility's water quality report, home test kits versus certified labs, and what to test for on a private well.
Water Filters
Pitchers, faucet and under-sink filters, reverse osmosis and whole-house systems: what each type removes, and which models are certified to do it.
Water Softeners
Hard water explained, salt-based versus salt-free systems, sizing, running costs, installation and how to compare installers.
Well Water
No utility tests a private well for you. What to test for and how often, and how to treat bacteria, iron, sulfur, nitrates and arsenic.