Water filter buying guide: test, match, then buy

Advertised prices, verified

The buying method, in order

1. Get evidence about your water first. On a city supply, read your utility's annual water quality report and note what it flags, then test at the tap for anything the house itself could add, like lead from old plumbing. On a well, a lab test is the foundation; our well water testing guide covers what to order and when.
2. Decide point of entry versus point of use. Problems that affect skin, laundry, appliances, and every fixture, such as hardness, iron, sulfur odor, or chlorine you can smell in the shower, call for whole-house treatment at the point of entry. Problems that only matter in drinking and cooking water are cheaper solved at one tap.
3. Match the media to the named contaminant. Carbon for chlorine, taste, and odor, with catalytic carbon where the utility uses chloramine. Softeners for hardness. Oxidizing systems for iron and sulfur. Reverse osmosis at the tap for dissolved contaminants like lead, arsenic, nitrates, or PFAS reduction. Each medium does its own job and none does all of them.
4. Shortlist by certification and running cost. Between systems of the same type, prefer models certified against recognized NSF/ANSI standards for your named contaminant, then compare purchase price and the recurring cartridge, media, or salt cost in the table below. The cheapest system to buy is often the dearest one to run.

The map of system types, in one pass

Pitchers, faucet mounts, and countertop units are the entry tier: carbon in small formats, good for taste and certified reductions at one glass at a time, with no installation. Under sink systems put bigger cartridges or reverse osmosis behind a dedicated tap, trading installation for capacity and better economics. Whole-house systems, cartridge or tank based, treat every drop entering the home and are the only answer for hardness, iron, sulfur, and shower-level chlorine.

Combinations are normal rather than excessive: a softener or whole-house carbon unit at the point of entry doing the bulk work, with reverse osmosis at the kitchen tap polishing the water people actually drink. Sequencing matters too, since softened or iron-free water protects the fine equipment downstream of it.

The mistakes this guide exists to prevent

Buying by fear is the expensive one: a contamination headline sells whole-house reverse osmosis to households whose actual test shows hard water and nothing else. The counter-move is boring and cheap, get the test, read the report, and let a named contaminant justify every dollar of equipment.

Ignoring running cost is the quiet one: every filter is a subscription to its own replacement media, and formats differ sharply in what that subscription costs. Before committing, price the cartridges or media in the table below at the interval the maker states, multiply by a few years of ownership, and compare systems on that number rather than the sticker.

Common questions

Do I really need to test before buying a filter?

Yes, because media are specialized: carbon does not soften, softeners do not remove lead, and nothing treats a contaminant you have not identified. A utility report or lab test turns the purchase from a guess into a fit.

Is one whole-house filter enough for everything?

Rarely. Whole-house units handle broad problems like chlorine, sediment, hardness, or iron, while dissolved drinking-water concerns are usually finished by a point-of-use system at the tap. Most solved homes run a combination.

What should I budget for a water filter system?

It spans from a pitcher to a whole-house install, which is why evidence comes first. The table on this page carries current vendor prices by system type, with typical systems near $1,531.

Are certifications on filters actually meaningful?

Certification against a recognized NSF/ANSI standard for a named contaminant means the claim was tested, not just printed. Prefer certified models when your purchase is driven by a specific reduction rather than taste.

Browse by system type

• Compare Water softeners on advertised prices
• Compare Salt-free softeners on advertised prices
• Compare Whole-house filters on advertised prices
• Compare Reverse osmosis systems on advertised prices
• Compare Shower filters on advertised prices
• Compare Countertop filters on advertised prices
• Compare Refrigerator filters on advertised prices
• Compare Iron filters on advertised prices