A. O. Smith · Under-sink filter
A. O. Smith AO-US-200 2-Stage Under Sink: what it removes and what it costs
Model: 2-Stage Under Sink Water Filter AO-US-200 (Claryum filtration, brushed nickel faucet), replacement AO-US-200-R
The A. O. Smith AO-US-200 2-Stage Under Sink is certified (NSF/ANSI 42, NSF/ANSI 53 and NSF/ANSI 401) to reduce PFAS (PFOA), lead, chlorine, chloramine, mercury and microplastics and 2 more of the contaminants we track. For 2 people drinking and cooking with it, replacement filters cost about $168 a year.
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8
certified reductions we track
17¢
filters per gallon at rated life
Price checked 2026-10-23. We may earn a commission.
What the A. O. Smith AO-US-200 2-Stage Under Sink removes
"Certified" means a certifier (NSF, WQA, IAPMO or CSA) lists this exact product for that reduction claim; the listing is linked. "Brand test only" means A. O. Smith cites a lab report but no certifier lists the claim. See certified vs. tested.
| Contaminant | Status | Evidence |
|---|---|---|
| PFAS | Certified | WQA listing, NSF/ANSI 53 ("PFOA") |
| Lead | Certified | WQA listing, NSF/ANSI 53 ("Lead") |
| Chlorine | Certified | WQA listing, NSF/ANSI 42 ("Chlorine") |
| Chloramine | Certified | WQA listing, NSF/ANSI 42 ("Chloramine") |
| Mercury | Certified | WQA listing, NSF/ANSI 53 ("Mercury") |
| Microplastics | Certified | WQA listing, NSF/ANSI 401 ("Microplastics") |
| Cysts | Certified | WQA listing, NSF/ANSI 53 ("Cyst") |
| VOCs | Certified | WQA listing, NSF/ANSI 53 ("VOCs") |
Not verified, either way (no certification or brand claim): Fluoride, Arsenic, Nitrate, Chromium 6, TDS, Bacteria and viruses, Iron, Copper, Uranium, 1,4-dioxane.
What it costs to run
Yearly cost = replacements per year × filter price, for each filter it uses; a filter is replaced at its gallon rating or its month limit, whichever comes first. Water use: drinking and cooking water (0.28 gallons per person a day, EPA's average adult intake).
| Household | Gallons a year | Filters a year | Total a year | Per gallon |
|---|---|---|---|---|
| 1 person | 102 | $168 | $168 | 164¢ |
| 2 people | 204 | $168 | $168 | 82¢ |
| 4 people | 409 | $168 | $168 | 41¢ |
Per-gallon costs in the table are for real use, so they also count any filter replaced at its month limit before it reaches its gallon rating. At rated filter life alone, filters cost 17¢ a gallon (the figure at the top of this page).
Replacement filters
| Filter | Rated life (gallons) | Rated life (months) | Price |
|---|---|---|---|
| AO-US-200-R 2-stage replacement filter | 500 Source note | 6 Source note | $83.99 Source noteBrand page MSRP aosmith.com |
Specs
- Type
- Under-sink filter
- Price
- $140
Source note
Brand page MSRP $139.99; A. O. Smith has no direct web store (sold through retailers). Seen 2026-10-23 aosmith.com
- Installation
- DIY (under-sink or inline fittings)
- Flow rate
- 0.5 gal/min
Source note
Rated flow per owner's manual performance table assets.aosmith.com
- Needs power
- No
Where it ranks
Compare the A. O. Smith AO-US-200 2-Stage Under Sink
Common questions
What does the A. O. Smith AO-US-200 2-Stage Under Sink remove?
The A. O. Smith AO-US-200 2-Stage Under Sink is certified (NSF/ANSI 42, NSF/ANSI 53 and NSF/ANSI 401) to reduce PFAS (PFOA), lead, chlorine, chloramine, mercury and microplastics and 2 more of the contaminants we track. For 2 people drinking and cooking with it, replacement filters cost about $168 a year.
Does the A. O. Smith AO-US-200 2-Stage Under Sink remove PFAS?
Yes. It is certified for PFOA reduction under NSF/ANSI 53 (WQA listing).
How much does the A. O. Smith AO-US-200 2-Stage Under Sink cost to run?
About $168 a year for 2 people ($168 for 1, $168 for 4), counting replacement filters, for drinking and cooking water (0.28 gallons per person a day, EPA's average adult intake).
Data checked 2026-10-23. 102 filters tracked.