Omnipure L5621
A NSF/WQA-certified under-sink filter that is certified to reduce 1 contaminant at about 1.0¢ per gallon.
As an Amazon Associate we earn from qualifying purchases — disclosure.
You want strong contaminant reduction at the kitchen tap without a countertop unit, and are comfortable with a simple under-cabinet install.
Certified for taste, odor, and chlorine (an aesthetic filter).
This is an aesthetic-standard filter (NSF 42) — it improves taste and reduces chlorine, but is not certified for health contaminants like lead or PFAS.
What is under-sink filter? A carbon-based cartridge (or set of stages) plumbed under your kitchen sink that filters the cold drinking-water line. Compare all filter types →
What it costs to own
| Upfront price | Check on Amazon → |
| Replacement filter (N/A) | $29Buy refill → |
| Estimated yearly cost (filters, ~1.5×/yr) | ~$44/yr |
| True cost per gallon | 1.0¢ |
Cost per gallon and yearly cost are our estimates from the rated capacity and current prices. The filter only works if you replace it on schedule.
What it's certified to remove
Certification is per-contaminant: the Omnipure L5621 is credited only for the contaminants listed here, verified by NSF/WQA. It does not imply removal of anything not listed.
✓ Verify this certification on the official NSF listing →
Full specifications
| Certified by | NSF, WQA |
| NSF/ANSI standards | 42 — reduces taste, odor, and chlorine (aesthetic standard) |
| Filter type | Under-sink filter |
| Rated capacity | 3,000 gallons |
| Flow rate | .5 gpm |
| Replacement element | N/A |
| Installation | Mounts under the sink; connects to the cold line. Basic DIY. |
Frequently asked
Is the Omnipure L5621 NSF certified?
Yes — the Omnipure L5621 is listed in the NSF, WQA certified-product database under NSF/ANSI standard 42. That means an independent body verified its claims (not just "tested to" a standard).
What does the Omnipure L5621 remove?
It is certified to reduce 1 contaminants: Chlorine / chloramine.
How much does the Omnipure L5621 cost per gallon?
About 1.0¢ per gallon, based on its rated capacity of 3,000 gallons and current price.
How often do you replace the under-sink filter?
A under-sink filter like this is typically replaced about 2 time a year (replacement element N/A). Replace on schedule — a spent cartridge stops reducing contaminants.
Compare similar under-sink filters
Source: NSF, WQA public certification listing. Specs and certified claims are from the official listing; cost figures are our estimates. Some links are affiliate links — see our disclosure.