Water Filters
Water Filters, Checked Against Their Certifications
Pitchers, faucet and under-sink filters, reverse osmosis and whole-house systems: what each type removes, and which models are certified to do it.
Pitchers & Dispensers
The cheapest way to filter drinking water: what pitchers and countertop dispensers can and cannot remove.
Faucet & Under-Sink
Filters that treat the water at one tap: faucet mounts, under-sink cartridges and what they are certified for.
Reverse Osmosis
How reverse osmosis works, what it removes, wastewater and remineralization, and how under-sink and countertop systems compare.
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.
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.
Whole-House Filters
Point-of-entry systems that treat every tap: when they make sense, sizing, installation and real costs.
Shower Filters
What a shower filter can realistically remove, which certification applies, and what the skin and hair claims rest on.