Aquasana Claryum Countertop (AQ-4000)
Faucet-connect countertop filter by Aquasana · Certified claims
Aquasana's US countertop page currently features the Clean Water Machine and lists no system price for the AQ-4000 (checked Oct 23, 2026); the AQ-4035 replacement set is $73.49 at Aquasana · checked October 23, 2026
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Our verdict
The set-and-forget champion: certified like a serious system, invisible like it is not there. If your faucet fits and you value certification over speed, this is the countertop filter most people should shortlist first.
Specifications & certification
| Type | Faucet-connect countertop filter |
| How it works | A slim housing that lives beside (or behind) the sink and connects to your faucet with a chrome diverter - twist the knob for filtered water, twist back for tap. Inside: activated carbon, catalytic carbon, ion exchange and sub-micron mechanical filtration. |
| Certification status | Aquasana states: 'WQA tested and certified to NSF/ANSI Standards 42, 53, and 401 for the claims specified on the Performance Data Sheet' - with Standard 53 including the P473 PFAS protocol. |
| Filter life | 450 gallons or up to 6 months per cartridge set |
| Replacement filters | AQ-4035 replacement set, $73.49 |
| Running cost | About $147/yr (two $73.49 sets) |
| Flow / pace | 0.4 gpm rated service flow - a glass fills in about 15 seconds |
| Size | About 7 in W x 9 in H x 4 in D - the smallest footprint here |
| Power & plumbing | None. Runs on water pressure. |
| Warranty | 1-year system warranty |
What it claims to reduce
These are Aquasana's own published figures, graded by the certification status above - we do not run a lab, and we do not upgrade a brand's wording.
- Up to 97% chlorine and chloramine (certified claims)
- 99% of cysts, lead, VOCs and asbestos (certified claims)
- 96% mercury and PFOS/PFOA (certified claims)
- Up to 99% of 78 contaminants (Aquasana)
Strengths
- Certified for lead, PFAS, VOCs and cysts - the full health list
- Almost no counter space; nothing to fill
- Instant filtered water on demand, no tanks
Trade-offs
- Slow flow (0.4 gpm) - patience for filling pots
- Cartridges every 6 months make running costs the highest of the faucet group
- Needs a standard-thread faucet - not for pull-down sprayers
Never miss a filter change
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