Aquasana AQ-4000 Review – Good or Bad Countertop Water Filter System?

    Aquasana AQ-4000 Review

    Aquasana AQ-4000 Countertop Water Filter

    •    Price: $
    •    Flow Rate: 0.5 gpm
    •    Filt. Capacity: 450 gal
    •    NSF Cert.: 42, 53, 401, P473
    •    Warranty: 1 Year

    The Aquasana AQ-4000 is a countertop filter system that converts plain tap water into clean, great-tasting drinking water on demand.

    Thereby, the unit does not require permanent installation to your plumbing system or kitchen sink whatsoever. Quite the contrary:

    The AQ-4000 which is available in 3 different finishes (white, black and brushed steel) attaches to faucets in a matter of minutes, no tools required.

    Once set up, the Claryum filter uses carbon and ion exchange media as well as sub-micron filtration to help you get rid of:

    • Chlorine and chloramines (>97%)
    • Heavy metals (lead >99.3%, mercury >95%.8)
    • Chlorine resistant cysts like giardia and cryptosporidium (>99.99%)
    • Organic chemicals including herbicides, pesticides and VOCs (between 95% and more than 99%)
    • Pharmaceuticals such as Estrone (96.5%) and Ibuprofen (95.4%)
    • PFOA and PFOS (96%)

    All reduction rates are according to official test data.

    Total number of contaminants removed: 77

    NSF certifications: Standards 42, 53, 401 + Protocol P473

    By the way, the flow rate you can expect is around .5 gallons per minute, so a bit slow. However, remember that a more thorough filtration requires either more time or higher pressure.

    One filter cartridges is rated at 450 gallons or 6 months. If you do the math, you will end up paying much less per gallon that you would buying bottled water.

    You just have to be careful because the Aquasana AQ-4000 is not compatible with all faucets. For example, it does not fit pullout sprayers. Most standard faucets are fine. Also, the package includes two adapters which come in handy if your faucet happens to be non-standard size.

    What We Like

    Usually when a filter system removes that many impurities it also eliminates some of the good stuff – think essential minerals. Not so with the AQ-4000. All calcium, potassium and magnesium will be preserved and contribute to your total daily mineral intake.

    Another advantage is that you can easily switch between filtered and unfiltered water without having to uninstall the unit. Simply pull or push the pin on the diverted valve as needed.

    This plus the compact size is also the reason why this countertop water filter is highly portable. And it doesn’t take up much space on your counter.

    Did we mention that everything is covered by a 1-year limited warranty?

    Aquasana countertop water filter review - AQ-4000


    Like we said, the Aquasana AQ-4000 is really simple to set up – no permanent fixtures or installation required!

    Here is what you need to do:

    1. Remove the aerator from your kitchen faucet.
    2. Make sure the rubber washer on the diverter valve sits in place.
    3. Attach the diverter valve. You may need to use one of the brass adapters (included). If so, tighten the adapter with the plastic hex wrench tool (included).
    4. Push the two hoses into the holes on the bottom of the unit (turning it upside down). The blue tip goes into the blue cap, the white tip into the white cap.
    5. Open your faucet and check for leaks.
    6. Pull out the diverter pin.
    7. Flush for 10 minutes.


    Here is a short video outlining the setup process step by step:

    The Package (Parts)

    • Unit with snap-on cover
    • Threaded cartridge caps
    • 2x O-rings
    • 2x filter cartridges
    • Faucet diverter valve and hose assembly
    • 2x brass faucet adapters, different sizes (13/16″ and 15/16″ male)
    • Rubber washers
    • Plastic hex wrench


    In theory, filter replacements couldn’t be more straightforward. All you really have to do is put the unit on its side, twist off the filter caps, take out the old cartridges and insert new ones – shouldn’t take more than 2 minutes, right?

    Yeah, not quite. The caps get easily stuck making the whole process a nightmare. Some customers would even order a whole new unit because they couldn’t manage to open their old one.

    A possible solution to this is to remove the blue filter first. Then use the fins on its end to twist the fins of the white filter. And make sure to not install both in the same direction. The white goes in nipple-first, the blue one the other way round.

    At least you only have to do this about every 6 months…


    If you are looking for a manual follow this link:

    What We Don’t Like

    Filter replacements are by far the biggest issue. After 6 months of use the filter caps are likely stuck having caused multiple incidences of bloody knuckles.

    In addition, replacements cartridges are also super expensive. They cost almost as much as a brand-new unit including filters.

    The next big issue are leaks. Either water will pour out the bottom of the unit or out of one of the hoses or the diverter. If the pin is leaking, it’ll spray water all over the place. The good news is that the manufacturer is usually willing to send replacement parts free of charge.

    And lastly, the diverter. It might get stuck due to corrosion or keeps popping out so that you can’t switch between pure and plain tap water anymore. A simple tip that we read about in one of the customer reviews is to grease the pin with vegetable oil.

    Our Verdict

    Bottom line: The Aquasana AQ-4000 provides pure water with great taste. Although there have been some major issues, for the majority of users the countertop system seems to do a great job as long as they keep changing filters on schedule.

    The system itself is affordable, the replacement cartridges not so much.

    Our verdict: 3.5 stars!

    Looking for More Aquasana Information & Reviews?

    You can find our full Aquasana Water Filters & Softener Guide with all the important information here:

    If you would prefer to read more countertop water filter reviews, follow this link:

    comment banner

    This completes our Aquasana countertop water filter review. If you have any questions, please don’t hesitate to leave a comment below!

    Leave a Comment: