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Learn · Water Inc.
Know what's in your water — and what it takes to remove it.
Filtration isn't one-size-fits-all, and not every filter does what it claims. Here's how to tell the difference, in plain language.
Why it matters
Why NSF certification matters.
There are no federal regulations governing residential water filters. A company can print "filters 99% of contaminants" on a box with no independent proof behind it. That's the gap NSF certification closes.
NSF International is an independent, accredited organization that writes the consensus standards (NSF/ANSI) for water treatment products and tests them against those standards. When a filter is NSF-certified for a specific claim, it means a third-party lab verified the product actually reduces that contaminant — and audits the manufacturer to confirm it keeps performing over time. It's the difference between a marketing claim and a tested, verified result.
The key thing to understand: certification is earned for each contaminant individually. A filter certified to NSF/ANSI 53 hasn't been proven to remove everything under that standard — only the specific contaminants listed on its performance data sheet. Always check what a filter is actually certified to reduce, not just which standard number it carries.
Not all filtration is the same
A filter is only as good as what it's built — and tested — to remove.
Two filters can look identical on the shelf and perform completely differently. The type of media, the contact time the water gets with it, and whether the product was certified for your specific concern all change the result. Here's how the common approaches compare.
| Type | What it does well | Watch-outs |
|---|---|---|
| Basic pitcher / faucet | Improves taste and odor; reduces chlorine. Inexpensive and easy. | Often certified only to NSF 42 (aesthetics). Small media volume means frequent replacement; many were never designed to reduce lead or PFAS. |
| Activated carbon block | Reduces chlorine, taste/odor, and — when certified to NSF 53/401 — health contaminants like lead, cysts, VOCs and emerging contaminants, while keeping beneficial minerals. | Performance depends on the carbon quality and contact time. Certification is per-contaminant — check the data sheet. |
| Reverse osmosis (RO) | Removes the widest range of dissolved contaminants, including TDS. Certified under NSF 58. | Wastes water to drain, removes beneficial minerals, slower flow, and needs more maintenance and space. |
The myth
"A filter is a filter — if it makes the water taste better, it's removing the bad stuff."
The reality
Better taste usually means chlorine reduction, which is an aesthetic improvement. Reducing health contaminants like lead, cysts, or PFAS is a separate, harder job that requires specific media and specific NSF certification to prove.
Decode the labels
What the NSF/ANSI standards actually mean.
When you see these numbers on a filter, here's what each one certifies.
Aesthetic effects
Certifies reduction of non-health contaminants that affect how water looks, tastes, and smells.
Covers: chlorine, taste & odor, chloramine, particulates, iron, manganese, zinc.
Health effects
Certifies reduction of contaminants with a potential health impact — the standard that matters most for safety.
Covers: lead, asbestos, cysts (Cryptosporidium), VOCs, chromium, certain PFAS.
Emerging contaminants
Certifies reduction of "contaminants of emerging concern" found at trace levels in tap water.
Covers: up to 15 contaminants including pharmaceuticals, pesticides, herbicides, and BPA.
PFOA & PFOS
A specific protocol for the "forever chemicals" PFOA and PFOS, verifying reduction below the EPA health advisory level.
Covers: PFOA and PFOS, two of the most-studied PFAS compounds.
Keep the protection
Why replacing your filter on schedule matters.
NSF certification is based on a filter's rated capacity — the volume of water it can treat before performance drops. Run a cartridge past that point and you lose the very protection you bought it for.
Capacity is finite
Each cartridge is certified to treat a set volume of water. Past that, contaminant reduction is no longer guaranteed.
Old filters can backfire
A saturated or neglected cartridge can become a place for bacteria to grow and can release trapped contaminants back into your water.
On-time is effortless
Our auto-ship program times each replacement to your system's rating — so you stay protected without tracking it yourself.
Filtration you can verify, delivered on time.
Every Body Glove system from Water Inc. is independently NSF-certified. Keep yours performing with worry-free filter delivery.
Set up Subscribe & SaveSources: NSF — NSF/ANSI 42, 53 and 401: Filtration Systems Standards; NSF — Standards for Water Treatment Systems. Educational information only; check each product's performance data sheet for its specific certified claims.
Get a quote built for your home.
Whole-house filtration isn't one-size-fits-all — it's sized to your water usage, plumbing, and local water quality. Tell us about your home and we'll put together a real quote, not a guess.