Under-sink reverse osmosis · checked 16 Oct 2026
A. O. Smith High Efficiency Reverse Osmosis System
Model AOS-HERO-CHR · replacement parts AOS-HERO-S1S3, AOS-HERO-S2
Lead:Brand says certifiedPFAS:Brand says certified
Each claim, checked
What the brand says, what a certification listing shows for this model, and where each fact comes from. We read listings; we do not test products.
- Certified (listing checked)The certifier’s public listing shows this claim for this model.
- Brand says certifiedThe brand says certified; IAPMO’s listing does not show it. NSF can be checked by hand.
- Brand claim onlyThe brand claims it without citing a certification.
| Contaminant | Brand claim | Standard | Certifier | Confirmed? | Source, date checked |
|---|---|---|---|---|---|
| Lead | “Lead pH 6.5 5 ug/L 99.8% Pass” brand source | NSF/ANSI 53 | WQA (named by brand) | Brand says certified — not found in IAPMO’s listing; check NSF | IAPMO searched · check NSF’s listingchecked 16 Oct 2026 |
| PFOA | “Perfluorooctanoic acid (PFOA) & Perfluorooctane sulfonate (PFOS) 0.00007 mg/L 97.4% 98.4% Pass” brand source | NSF/ANSI 58 | WQA (named by brand) | Brand says certified — not found in IAPMO’s listing; check NSF | IAPMO searched · check NSF’s listingchecked 16 Oct 2026 |
| PFOS | Same statement as for PFOA. brand source | NSF/ANSI 58 | WQA (named by brand) | Brand says certified — not found in IAPMO’s listing; check NSF | IAPMO searched · check NSF’s listingchecked 16 Oct 2026 |
| Arsenic | “Arsenic Pentavalent 0.010 mg/L 88% 96% Pass” brand source | NSF/ANSI 58 | WQA (named by brand) | Brand says certified — not found in IAPMO’s listing; check NSF | IAPMO searched · check NSF’s listingchecked 16 Oct 2026 |
| Fluoride | “Fluoride 1.5 mg/L 85% 90% Pass” brand source | NSF/ANSI 58 | WQA (named by brand) | Brand says certified — not found in IAPMO’s listing; check NSF | IAPMO searched · check NSF’s listingchecked 16 Oct 2026 |
| Nitrate | “Nitrate/Nitrite 10 mg/L 74% 78% Pass” brand source | NSF/ANSI 58 | WQA (named by brand) | Brand says certified — not found in IAPMO’s listing; check NSF | IAPMO searched · check NSF’s listingchecked 16 Oct 2026 |
| Total dissolved solids (TDS) | “TDS 187 mg/L 95.7% 96.4% Pass” brand source | NSF/ANSI 58 | WQA (named by brand) | Brand says certified — not found in IAPMO’s listing; check NSF | IAPMO searched · check NSF’s listingchecked 16 Oct 2026 |
| Chromium-6 | “Chromium Hexavalent 0.1 mg/L 97% 98% Pass” brand source | NSF/ANSI 58 | WQA (named by brand) | Brand says certified — not found in IAPMO’s listing; check NSF | IAPMO searched · check NSF’s listingchecked 16 Oct 2026 |
| Chlorine | “Chlorine Reduction, Free Available ≥50% 96.8% Pass” brand source | NSF/ANSI 42 | WQA (named by brand) | Brand says certified — not found in IAPMO’s listing; check NSF | IAPMO searched · check NSF’s listingchecked 16 Oct 2026 |
| Chloramine | “Chloramine Reduction, Free Available 0.5 mg/l 96.8% Pass” brand source | NSF/ANSI 42 | WQA (named by brand) | Brand says certified — not found in IAPMO’s listing; check NSF | IAPMO searched · check NSF’s listingchecked 16 Oct 2026 |
| VOCs (volatile organic chemicals) | “VOC Surrogate Test See Table 8.2 99.7% Pass (as chloroform)” brand source | NSF/ANSI 53 | WQA (named by brand) | Brand says certified — not found in IAPMO’s listing; check NSF | IAPMO searched · check NSF’s listingchecked 16 Oct 2026 |
| Cysts (Giardia, Cryptosporidium) | “Cyst Live Cryptosporidium & Giardia 99.95% 99.997% Pass” brand source | NSF/ANSI 53 | WQA (named by brand) | Brand says certified — not found in IAPMO’s listing; check NSF | IAPMO searched · check NSF’s listingchecked 16 Oct 2026 |
| Microplastics | “Microplastics At least 10,000 ≥85% 99.3% Pass” brand source | NSF/ANSI 401 | WQA (named by brand) | Brand says certified — not found in IAPMO’s listing; check NSF | IAPMO searched · check NSF’s listingchecked 16 Oct 2026 |
| Pharmaceuticals | “Ibuprofen 60 ng/L 95.1% 95.3% Pass” brand source | NSF/ANSI 401 | WQA (named by brand) | Brand says certified — not found in IAPMO’s listing; check NSF | IAPMO searched · check NSF’s listingchecked 16 Oct 2026 |
Filter changes, by the brand’s numbers
How often A. O. Smith says to replace each part. Real filter life depends on how much water you use and what is in it.
| Part | Brand says replace every | Changes a year | Source, date checked |
|---|---|---|---|
| Carbon block filters for stages 1 and 3 (AOS-HERO-S1S3) | 6 months or 365 gallons“Carbon Block Replacements for Stage 1 and 3 for the Reverse Osmosis System. Replace every 6 month or 365 gallons.” | 2 | brand sourcechecked 16 Oct 2026 |
| RO membrane (AOS-HERO-S2) | 12 months“Reverse Osmosis Membrane for the Reverse Osmosis System. Replace every 12 months.” | 1 | brand sourcechecked 16 Oct 2026 |
Certification listings found
No IAPMO R&T listing matched this model when we searched on 16 Oct 2026.
Check it yourself
NSF’s and WQA’s terms don’t allow automated lookups, so these links open their public listings for this model:
- NSF listing search: AOS-HERO-CHR
- NSF listing search: AOS-HERO-S1S3
- NSF listing search: A.O. Smith
- WQA listing search: AOS-HERO-CHR
- WQA listing search: AOS-HERO-S1S3
- WQA listing search: A.O. Smith
- IAPMO R&T listing directory
What the brand says about certification
- “NSF/ANSI Standard 42: Yes | NSF/ANSI Standard 53: Yes | NSF/ANSI Standard 58: Yes | NSF/ANSI Standard 401: Yes” source checked 16 Oct 2026
- “System Tested and Certified by WQA International against NSF/ANSI Standards 42, 53, 58 and 401 for the reduction of the claims specified on the Performance Data Sheet and at www.wqa.org.” source checked 16 Oct 2026
Performance data sheet (names WQA)