A plain comparison of reverse osmosis, under-sink carbon and pitcher filters: what each reduces, upkeep, water waste and cost, plus a quick way to decide which one fits your water.
Independent water filter guides
Find the water filter that's certified for what's in your water.
Most filters are sold on taste. GudWater starts from your water report, checks NSF/ANSI certifications, and cites the EPA and peer-reviewed research, so you don't pay for a filter that solves the wrong problem.
What are you worried about?
Pick the problem first. The right filter type follows from it.
Filter types, compared
Six designs, from a $25 pitcher to a whole-house system. Each card lists the certifications that matter for it.
Pitchers and dispensers
Better taste, renters, small households, and some lead or PFAS reduction depending on the cartridge.
Faucet-mount filters
Filtered water on demand without plumbing work.
Under-sink carbon systems
Households that drink a lot of tap water and want more capacity with less upkeep.
Reverse osmosis (RO)
The broadest reduction, including PFAS, nitrate, arsenic and dissolved solids.
Countertop and gravity systems
Renters who want more capacity than a pitcher, or households preparing for emergencies.
Whole-house (point of entry)
Chlorine taste in showers, sediment, hardness, and well water treatment.
Brands we cover
What each brand makes, and what to check before you buy.
Latest guides
Every guide lists its sources and the date we last checked them.
Reverse osmosis and two-stage filters removed 94% or more of PFAS in a Duke and NC State study, while carbon pitchers were inconsistent. Here's what that means, plus the current EPA PFAS rules.
What NSF/ANSI 42, 53, 58, 401, 44, 55 and 244 mean on a water filter box, why the standard number alone isn't enough, and how to check a model's certified claims in two minutes.
There is no known safe level of lead exposure. Learn where lead in tap water comes from, how to test, the new 10 ppb federal action level, and how to pick a filter certified for lead.
Know when the rules change
EPA limits for lead and PFAS are changing over the next few years. Get a short email when something changes that affects which filter you should use. No spam, unsubscribe anytime.