Treatment Guides · PurityMap Journal
Choosing a Water Filter by Contaminant: PFAS, Lead & More
The right filter depends entirely on what you are trying to remove. Match the technology to your actual finding, not to marketing.
Key takeaway
The right filter depends entirely on what you are trying to remove. Match the technology to your actual finding, not to marketing.01
Start with your finding, not a product
A filter that is excellent for hard water may do nothing for PFAS, and vice versa. Before you buy, open your city water report so you know which contaminants are actually on the record — and if it matters for your home, run a test of your own tap. Then match the technology to the concern.
02
PFAS: reverse osmosis or certified carbon
For PFOA and PFOS, choose reverse osmosis (RO) or an activated-carbon block specifically certified for PFAS reduction. RO is the most thorough; a certified under-sink or countertop unit handles a household's drinking and cooking water. Look for NSF/ANSI certification for PFOA/PFOS, not a generic 'purifier' claim.
03
Lead: NSF/ANSI 53 certified
For lead, the key is the certification, not the format. A faucet or pitcher filter certified to NSF/ANSI 53 for lead reduction is a low-cost, no-plumbing option; RO removes lead as well. Confirm the specific model's listing before buying, and see reading a lead result on your report for context.
04
Arsenic and nitrate: reverse osmosis
For arsenic and nitrate — common in some groundwater and agricultural areas — reverse osmosis is the most accessible point-of-use option; anion exchange and, for arsenic, adsorptive media also work. These are worth prioritizing if you are on a private well, which federal monitoring does not cover.
05
Hard water: a softener, not a health filter
Hardness is an aesthetic and plumbing matter, not a health contaminant, and is excluded from the health-based Purity Score. An ion-exchange softener or salt-free conditioner addresses scale and soap performance; it is not a contaminant filter. See do you need a water softener for the decision.
06
One honest caveat
Certified lab performance assumes correct installation and timely cartridge changes. A filter past its rated capacity can stop working. Set a replacement reminder the day you install it, and re-test to confirm it is doing the job. PurityMap may earn an affiliate commission on some product links, at no cost to you.
07
Health disclaimer
This article gives general guidance on treatment technology. It is not medical advice and does not determine whether any water is fit for a specific person. For health concerns about a specific contaminant, consult a licensed healthcare professional, and use a certified laboratory to test your own water.
What the evidence supports
Authored analysis
The article sections above are the published interpretation for this topic, tied to the source list below.
What it does not tell us
This editorial record alone cannot determine a household’s exposure, diagnose a health condition, or replace current system-level evidence.
Methodology note
Treatment matches reflect NSF/ANSI 53 (health-effects reduction) and 58 (reverse osmosis) certification scopes and EPA treatment-technique guidance. No product brands or performance figures are asserted; certification for the specific contaminant is the standard referenced.
Sources citedThese are the source citations published with this article. Open the data-source library to understand how PurityMap handles provenance and limitations.
- 01
NSF/ANSI 53 (health-effects reduction) and NSF/ANSI 58 (reverse osmosis) certification standards.
- 02
US EPA — treatment technique guidance for drinking-water contaminants. https://www.epa.gov/sdwa