A. O. Smith · Under-sink reverse osmosis
A. O. Smith Direct Flow RO AOS-DFRO800: what it removes and what it costs
Model: AOS-DFRO800-BN (brushed nickel faucet; AOS-DFRO800-NF variant); filters AOS-DFRO-CPP, AOS-DFRO-ROM
The A. O. Smith Direct Flow RO AOS-DFRO800 is certified (NSF/ANSI 58) to reduce TDS. A. O. Smith also claims chlorine from lab tests that are not certification. For 2 people drinking and cooking with it, replacement filters cost about $290 a year, and it sends about 115 gallons a year to the drain.
1
certified reductions we track
40¢
filters per gallon at rated life
Price checked 2026-10-23. We may earn a commission.
What the A. O. Smith Direct Flow RO AOS-DFRO800 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 |
|---|---|---|
| TDS | Certified | IAPMO R&T listing, NSF/ANSI 58 ("TDS") |
| Chlorine | Brand test only | A. O. Smith (own test to NSF/ANSI 42, per PDS): "Chlorine (99.4%)" |
Not verified, either way (no certification or brand claim): PFAS, Lead, Chloramine, Fluoride, Arsenic, Nitrate, Chromium 6, Mercury, Microplastics, Cysts, VOCs, 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, plus the water sent to the drain at an average water and sewer price. 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 | Drain water | Total a year | Per gallon |
|---|---|---|---|---|---|
| 1 person | 102 | $290 | 57 gal ($1) | $291 | 285¢ |
| 2 people | 204 | $290 | 115 gal ($2) | $292 | 143¢ |
| 4 people | 409 | $290 | 230 gal ($5) | $295 | 72¢ |
Per-gallon costs in the table are for real use, so they also count drain water and any filter replaced at its month limit before it reaches its gallon rating. At rated filter life alone, filters cost 40¢ a gallon (the figure at the top of this page).
Rated production is 800 gallons a day; 2 people need about 0.56 — well within it. Colder water and lower pressure reduce actual output.
Replacement filters
| Filter | Rated life (gallons) | Rated life (months) | Price |
|---|---|---|---|
| AOS-DFRO-CPP stage 1 & 3 composite | 365 Source note | 6 Source note | $79.99 Source noteMSRP aosmith.com |
| AOS-DFRO-ROM RO membrane | 730 Source note | 12 Source note | $129.99 Source noteMSRP aosmith.com |
Specs
- Type
- Under-sink reverse osmosis
- Price
- $575
Source note
Brand MSRP; aosmith.com shows MSRP and links to retailers 2026-10-23 aosmith.com
- Installation
- DIY (under-sink or inline fittings)
- Rated production
- 800 gallons per day
Source note
- Pure to drain
- 1.78:1 est.
Source note
Derived from PDS rated efficiency 64% (64/36); brand states no ratio assets.aosmith.com
- Flow rate
- 0.56 gal/min
Source note
Water flow at faucet assets.aosmith.com
- Needs power
- Yes
- Remineralization
- No
Compare the A. O. Smith Direct Flow RO AOS-DFRO800
Common questions
What does the A. O. Smith Direct Flow RO AOS-DFRO800 remove?
The A. O. Smith Direct Flow RO AOS-DFRO800 is certified (NSF/ANSI 58) to reduce TDS. A. O. Smith also claims chlorine from lab tests that are not certification. For 2 people drinking and cooking with it, replacement filters cost about $290 a year, and it sends about 115 gallons a year to the drain.
Does the A. O. Smith Direct Flow RO AOS-DFRO800 remove PFAS?
It has no certifier listing or brand claim for PFAS reduction.
How much does the A. O. Smith Direct Flow RO AOS-DFRO800 cost to run?
About $292 a year for 2 people ($291 for 1, $295 for 4), counting replacement filters and the water sent to the drain, 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.