How We Research
Every guide here starts with one question: will this filter work for the person who is shopping for it? For water filters, that means your counter space, how much water your household uses and how much upkeep you'll put up with.
Here is how we answer it.
1. We start with your kitchen
One person, a couple and a family of five use different amounts of water. A tall gravity filter may not fit under your cabinets, and a reverse osmosis unit needs an outlet.
We check the size, footprint and power needs the maker lists. When your kitchen limits the choice, we say what to look for.
2. We compare specs and features
We look at the filter type, tank or pot size, how many filter stages there are, what filters cost to swap and how often, and any wastewater ratio on reverse osmosis units.
We also note the standards a maker names, like NSF/ANSI 42, 53, 58, 372 or 401. Makers describe their filters in their own words, so we name the brand for every claim.
3. We look at buyer feedback
We read through what buyers report after using a filter. We look for patterns, like slow flow, leaks, noisy pumps, costly filter swaps and parts that are hard to clean.
One angry review doesn't sink a product. A pattern does.
4. We score each product
Our score weighs specs, features and buyer feedback against what you're shopping for. A product that's great for one reader may score lower in a guide written for another.
Scores spread out on purpose. A 10 is rare.
5. We keep pages up to date
Products change, and some disappear from stores. Many models come in several versions with close names, so we check each model number and we only link new units.
We skip unknown brands with no track record and any filter with a known recall. When we update a guide, the "Updated on" date at the top changes with it.
What our picks are not
Our picks are research, not lab tests. We don't claim to have used every filter we cover.
A certification label tells you what a model was tested for, and only that model. Before you rely on one, look up the exact model number in the NSF or IAPMO database.
We never say a filter cures, treats or prevents illness, and we don't call any filter safe for every kind of water. We label maker claims as the maker's claims.