How to Filter Tap Water at Home: Filters, NSF Labels, and Water Reports
Not every filter does the same job. Start with your water report, then match the filter to what you actually want to reduce.
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The short version
You may not need a filter at all. Read your water report first, then pick a filter certified for the exact thing you want to reduce, and change the cartridge on time.
Begin with the water you actually have
A filter is most useful when it deals with a real water quality concern. In the United States, community water systems publish an annual Consumer Confidence Report. It summarizes testing and regulatory information. Private wells need their own testing. A filter bought for taste is not necessarily designed to reduce lead or PFAS.
How to read a water quality report
Look for the contaminant name, the level detected, the legal limit and any violations or explanations. The maximum contaminant level goal is a health based goal, while the maximum contaminant level is the enforceable standard. The report describes the water system, so it may not show contamination that comes from the plumbing inside your home.
NSF/ANSI 42 and 53
NSF/ANSI 42 generally covers things you notice, such as taste and odor. NSF/ANSI 53 covers specific health related contaminants. A product certified to a standard is not automatically certified for every contaminant in that standard, so check the exact claim and the model listing.
NSF/ANSI 58 and 401
NSF/ANSI 58 is for reverse osmosis systems, and NSF/ANSI 401 covers reduction claims for certain emerging compounds. Certification language can be confusing because brands often list several standards. Search the certifier’s directory for the exact product and the contaminant you want reduced.
Pitcher, faucet and under sink filters
Pitchers are affordable and portable but need frequent cartridge changes. Faucet filters are convenient where they fit. Under sink systems are discreet and may have more capacity. Reverse osmosis also comes with installation, upkeep and water use to think about. Performance varies by model, not just by type.
Maintenance is part of filtration
A filter that is overdue for replacement may not work as advertised. Follow the cartridge schedule and the sanitation instructions, and note any warnings about water that is not microbiologically safe. If your concern is lead, PFAS or a local advisory, use guidance for that specific contaminant, and do not treat a taste filter as a substitute.
What a water report cannot tell you
A report from your water company describes the water that leaves the treatment plant. It cannot show what your own pipes add on the way to your tap. Lead, for example, can come from older plumbing or fixtures inside a home. If your house is older, ask your water company about testing options and read current guidance on lead before you decide what to buy.
Do you even need a filter?
Maybe not. Plenty of homes have water that meets standards and tastes fine. A filter makes sense when your report shows something you want to reduce, when you have a local advisory, when your plumbing is old, or when taste and smell bother you. Spending money on a system you do not need is a common mistake.
Think about cost over a year
The sticker price is only part of it. Pitchers are cheap up front but you replace cartridges often. Under sink systems cost more at the start and then replace filters less often. Work out the cost for a year, including cartridges, and divide by the gallons you actually use. That tells you more than the box does.
Renting or short on space
If you rent or have a small kitchen, a pitcher or a faucet mounted filter needs no installation and moves with you. Check that the model fits your faucet, and keep the receipt in case it does not.
When to ask someone else
If you are on a private well, use a state certified lab for testing, because a public water report will not apply to you. If your area has a boil water notice, follow it. If you mix baby formula, ask your pediatrician what water to use.
Quick questions
Does boiling water remove PFAS?
No. Boiling does not remove PFAS, and it can concentrate some contaminants as water evaporates. Look for a filter certified to reduce PFAS instead.
What is the difference between NSF 42 and 53?
NSF/ANSI 42 covers things like taste and odor. NSF/ANSI 53 covers health related contaminants such as lead. Check which one applies to what you want to reduce.
How often should I replace a water filter?
Follow the schedule from the maker, usually based on gallons or months, whichever comes first. An overdue filter may not work as advertised.
The swaps
Where to start when you shop.
| Instead of | Consider | Check first |
|---|---|---|
| A pitcher sold for taste | A filter certified for the contaminant on your water report | The exact model in the NSF listing for that claim |
| Boiling water to ease PFAS worries | A certified filter, such as reverse osmosis or one with a PFAS claim | The claim is listed for that model, plus the cartridge schedule |
Brand names are examples to research, not a promise. Always check current details before you buy.
Your next step
Find your latest water report and write down the one contaminant you care about most. Then check the filter listing for that exact claim. Our beginner swap list shows where this fits.
Where to read more
The EPA and CDC both explain Consumer Confidence Reports, and NSF publishes its drinking water treatment standards. Check the current pages.
Part of our Non-Toxic Living series
Start with Non-Toxic Living for Beginners. Next, try Cleaning basics or Indoor air quality.
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Ten small swaps, in the order that makes the most difference.
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