Review: Aquasana OptimH2O Reverse Osmosis System

This page may contain affiliate links. If you buy a product or service through such a link we earn a commission at no extra cost to you. Learn more.

In this review, you’ll learn about the advantages and drawbacks of the Aquasana OptimH2O Reverse Osmosis System aka the Aquasana OptimH2O Reverse Osmosis + Claryum.

In a nutshell, the system features a 3-stage filtration process with an additional remineralization stage – adds bits of healthy minerals – to provide crystal clean and great-tasting drinking water. 4 NSF certifications guarantee the effective removal of a broad range of contaminants making the Aquasana OptimH2O RO system perfect for people who don’t want to make compromises when it comes to drinking water quality. The price? Fair!

Want all the details? Continue reading…

Aquasana OptimH2O Reverse Osmosis System

Aquasana OptimH2O Reverse Osmosis System

Price: $$
Filter Stages: 4
Water Flow: Not Specified
NSF Certifications: 42, 53, 58, 401
Annual Cost: ~$240

Overall Rating: 4.5/5.0 ⓘRating based on filtration performance, filter life, price and yearly cost, NSF testing/certification, customer support, product warranty, our testing/experience, user feedback, and other factors.

Aquasana OptimH2O Reverse Osmosis System – All Specs

  • Model: OptimH2O
  • Annual Maintenance Cost: ~$240
  • Filter Media/Process: Activated Carbon, RO Membrane, Activated + Catalytic Carbon + Ion Exchange Resin, Remineralization
  • Filter Stages: 4
  • Membrane Rating: 35 gpd
  • Recovery Rate: 29.43%
  • Filtering Capacity: 365 gal
  • WxHxD (System): 12″x12.5″x4.5″
  • Tank: 11″x16″x11″, 3.2 gal
  • Water Temperature: 40-100 °F
  • Water Pressure: 40-100 psi
  • Water pH: 4-10
  • NSF Certifications: 42, 53, 58, 401
  • Warranty: 2 Years

Aquasana OptimH2O – Key Features

Let’s start with the 4-stage filtration process of the Aquasana OptimH2O:

  • Filter stage 1: A basic activated carbon filter reduces chlorine and organics like pesticides and VOCs, and traps larger particles. As a result, your water will not only taste and smell much better, the reverse osmosis membrane at the heart of the system is also protected from aggressive substances.
  • Stage 2: The reverse osmosis membrane reduces most potentially harmful contaminants such as nitrates & nitrites, lead, cysts, and pentavalent arsenic.
  • Filter stage 3: Claryum which is Aquasana’s proprietary, submicron mixture of activated + catalytic carbon as well as ion exchange resin helps to eliminate 5 times more contaminants – this is according to Aquasana – than the RO process would alone. This includes herbicides, pesticides, chloramines, a bunch of heavy metals, pharmaceuticals and more.
  • Remineralization stage: Finally, it’s time to get those healthy minerals that were lost during RO filtration back into your water. The mix of calcium, magnesium, and potassium also helps to balance water pH and alkalinity, and creates a natural taste. The remineralization stage is also why when testing the purified water with a TDS meter it won’t read “0”, which is not a water quality issue!

The full system is tested and certified to NSF/ANSI standards 42, 53, 58, and 401 (more on this below). Needless to say that if you are looking for a filter to finally get rid of those nasty contaminants lurking in your water the Aquasana OptimH2O RO system is it! It is guaranteed to remove up to 99% of 88 different contaminants, including chlorine, chloramine, and cyst, heavy metals like mercury, lead, arsenic 5, cadmium, and chromium 6, fluoride, nitrate/nitrite, overall TDS, trace pharmaceuticals and pesticides, PFOA & PFOS, MTBE, and VOCs.

And as far as filtration capacity is concerned, real-life daily water production is 13.32 gallons. This may not be as much as you get with other reverse osmosis filter models, but for regular household use it should be enough. Plus, we have a 3.2-gallon tank which stores water for later use.

And lastly, the system wastes about 3-4 gallons of water for every gallon filtered. This sounds like a lot but it’s actually pretty average for RO systems that don’t utilize a pressure pump.

Filter life: 365 or 6-12 months. Annual filter replacement cost: $240.

Aquasana Reverse Osmosis Pros

There’re a few additional benefits we’d like to mention.

First of all, system installation and maintenance are DIY-friendly. A user manual with detailed step-by-step instructions is part of the package, plus you can check out the helpful videos on YouTube.

Next, you can choose from 3 dedicated, full-metal faucet designs to match your kitchen decor: Chrome, brushed nickel, and oil-rubbed bronze.

And last but not least, Aquasana offers a 2-year limited warranty as well as a 90-day satisfaction guarantee on this product which got you covered in case something goes wrong.

What Contaminants Are Being Removed?

As mentioned before, the Aquasana OptimH2O RO system is NSF-certified to remove 88 different contaminants. Here is an excerpt from the performance data sheet:

  • Chlorine (97.66%)
  • Chloramine (97.66%)
  • Cyst (99.99%)
  • Mercury (95.8%-96.5%)
  • Lead (99.3-99.4%)
  • Asbestos (99%)
  • Arsenic 5 (97.6%)
  • Cadmium (95.3%)
  • Chromium 6 (97%)
  • Fluoride (95.7%)
  • Nitrate/nitrite (82.4%)
  • Overall TDS (95%)
  • Trace pharmaceuticals and pesticides (up to 98%)
  • PFOA & PFOS (96%)
  • MTBE (86.6%)
  • VOCs (up to 99%)

Aquasana OptimH2O Reverse Osmosis System

The Aquasana OptimH2O – learn more on


The full package includes the first set of filters as well as all the bits and pieces that are required to set everything up.

Overall, the Aquasana OptimH2O is quite easy to install. All you need is some patience, and you want to make sure to follow every single step as disclosed in the user manual – especially when it comes to installing the hoses.

That said, in case you’ve never drilled a hole before and you haven’t heard of a tool called wrench, then it’s probably a better idea to have a professional do the installation for you.

Tools and materials needed for installation:

  • Sharp utility knife
  • Tape measure
  • Phillips head screwdriver
  • Adjustable wrench
  • Cordless drill
  • 1/8” and 7/32” drill bits
  • Bleach
  • Safety glasses
  • Masking tape
  • Pencil
  • Bucket

Before you begin the installation process, make sure to place the entire system including the storage tank, manifold, and remineralization stage under the sink and check to make sure there is enough room. Also, be sure to measure and mark the lengths of 3/8” tubing needed to connect the tank and manifold as well as the faucet stem and remineralization stage.

To install the system, follow these steps:

Please consider these instructions as a general guideline. Always make sure to check and follow your user manual before getting started.
  1. The first step is installing the included brass Tee fitting to your cold water supply.
    1. First, shut off the cold water supply under your sink. Then, open the faucet to release any pressure and water remaining in the line.
    2. Remove the cold water line from the cold water connector under your sink. Install the included Tee fitting by hand and then tighten using an adjustable wrench.
    3. Connect the included white-colored ¼” tubing to the brass tee while leaving the other end unattached.
  2. Next up, you’ll need to install the water tank inside your under sink cabinet.
    1. First, apply 4 to 5 wraps of plumber’s tape around the threads on the tank fitting in the same direction as the threads.
    2. Connect the tank connector to the tank nipple and hand tighten. Be cautious not to overtighten or cross-thread this component.
    3. Position the storage tank close to the manifold. Measure and mark a length of white-colored 3/8” tubing long enough to connect the tank and manifold outlet. Make sure you also have enough tubing left over to connect the remineralization stage with the RO faucet. Use your utility knife to cut the tubing to the correct length.
    4. Install the white color tubing line to the tank connector outlet. This is done by pressing the tubing through the compression nut, sleeve, and collar. Then, loosen the compression nut and check that the tubing is fully connected. Connect the nut to the corresponding threads and tighten using an adjustable wrench.
  3. The next installation stage involves installing the system manifold.
    1. First plan out your installation location inside the under sink cabinet. You’ll need four to six inches of clearance underneath the manifold to change the filter cartridges easily. To get a better idea of what the system will look like once installed, pop the two outside filters into the manifold when marking the installation location.
    2. Now, use a pencil or pen to mark the screw locations for the manifold bracket. Also, mark the mounting location for the final remineralization stage 1-2 inches right from the rest of the unit.
    3. Use your drill and 1/8” bit to bore two holes for the manifold bracket. Then drive the two screws into the wall being sure to leave about half an inch exposed.
    4. If you still have the outer filters in place, remove them at this point. Then, attach the manifold bracket to the wall and secure it in place. Mount the remineralizer mount to the wall at this point as well.
  4. This stage involves installing the RO faucet. This requires a 1” diameter hole on the sink or countertop, which you may need to drill from scratch unless you have an existing hole for a soap dispenser or a water jet. The drilling process is typically the slowest and most difficult portion of the installation, so you’ll need to be patient and drill carefully.
    1. After the hole is completed, insert the included rubber gasket into the faucet base. Then, slide the entire faucet assembly through the hole.
    2. On the underside other faucet, attach the nut, spacer, and washer to the threaded portion of the faucet and tighten until secure. Then, mount the white-colored quick-connect fitting to the bottom of the threaded stem.
    3. Attach 3/8” while-colored tubing to the quick connect fitting. Pull on it gently to make sure it’s attached securely. Don’t connect the other end to the tank at this time.
  5. Next up is installing the RO drain connector to the drain pipe underneath your sink. This will involve drilling a hole in your drainpipe and installing a drain saddle.
    1. First, plan out your drain connector installation location. It should be installed before the P-trap and if possible on a different line than the garbage disposal. If you don’t have an installation location on a different line, then you’ll need a specialized garbage disposal connector.
    2. Slide the protective cover out of the drain connector. Position the drain connector in its installation location and fasten the nuts and screws to tighten in position.
    3. Using the hole inside the drain connector as your guide, drill a 7/32” hole into your drain pipe. Be slow and deliberate during this process, as you don’t want to drill through the opposite end of your drain pipe.
  6. At this point, you’ll need to make the necessary tubing connections throughout the system. As a general guide, tubing connections should be inserted a full inch into their respective fittings. You don’t want to have excessively long tubing as this can lead to kinks, crimping, and even leaks. After marking and measuring carefully, cut your tubing lengths to the appropriate size. Consult the manual for detailed illustrations and instructions for making the tubing connections, but this will give you the basic idea.
    1. First, connect the white tubing on the brass Tee to the cold water inlet with the inlet on the manifold.
    2. Next, connect the red tubing on the manifold outlet to the inlet on the remineralization stage.
    3. Then, connect the white tubing on the remineralization outlet to the RO faucet.
    4. Now, connect the white tubing currently attached to the storage tank to the manifold.
    5. Now, you’ll need to attach the air gap in the RO faucet to the RO membrane. This is important to ensure that a blocked drain connection can’t cause backward flow in the system and damage the filters/membrane.
    6. Last, you’ll need to run the red tubing from the RO faucet to the drain connector.
  7. Now, we’ll need to install the filters and RO membrane into their respective housings. The carbon and Claryum filters should already be installed (inside the red and yellow housings).
    1. First, mount the red housing in the first position. Push it into place making sure the connections are lined up and then rotate counterclockwise until tight.
    2. Repeat the above step for the RO membrane as well as the final Claryum filter stage.
  8. At this point, the installation process is essentially complete. All that remains is sanitizing, purging, and testing the system to get it ready for use.
    1. The first step is sanitizing the system. This should be done after installation as well as after regular filter replacements.
      1. Turn off the cold water supply to the system.
      2. Then, open the RO faucet to drain the storage tank and any water and pressure in the plumbing lines.
      3. Using unscented household bleach and the included eyedropper, add 3ml of bleach to the eyedropper.
      4. Then, disconnect the white tubing from the manifold outlet and insert the bleach.
      5. Relink the white tubing to the manifold outlet.
      6. The sanitizing process will begin during the following two steps.
    2. Testing the Pressure
      1. Turn on the cold water supply under your sink at this point.
      2. Open your normal kitchen faucet to purge it of pressure. When water runs normally, close this faucet.
      3. Double-check your RO faucet to make sure it’s shut.
      4. After two hours, the pressure inside the system will increase significantly. Check all of the fittings for leaks at this point. Should you find any, make sure the tubing is inserted fully and cut squarely.
    3. Finally, we will purge the system to prep the filters and RO membrane, and sanitize the tank. To accomplish this simply open the RO faucet, and allow the water to flow for a full day. After that, shut off the faucet, and the process is finished!


The Package (Parts)

  • System Manifold
  • Carbon Filter Sump
  • Membrane Filter Sump
  • Claryum Filter Sump
  • Remineralizer
  • Faucet
  • Gasket, Nut, Washer, Spacer, Quick Connector (for faucet)
  • Water Storage Tank
  • Eye Dropper
  • Tank Connector
  • Plumber’s Tape
  • Drain Connector
  • Nuts & Bolts
  • Foam Seal
  • Flow Restrictor & 90° Elbow
  • Tubing 1/4″ White
  • Tubing 3/8″ White
  • Tubing 3/8″ Red
  • Screws + Bracket
  • Brass Tee
  • Carbon Filter Cartridge
  • Claryum Filter Cartridge


Aquasana’s OptimH2O reverse osmosis water filter system is definitely low in maintenance. The filters housings easily twist on and off. And we have quick-connect fittings. Both make changing the filter elements a painless process.

Here’s how often you need to replace each component as per manufacturer specifications:

  • Carbon pre-filter: About every 6 months or 365 gallons
  • RO membrane: About every 12 months or 365 gallons
  • Claryum post-filter: About every 6 months or 365 gallons
  • Remineralization filter: About every 12 months or 365 gallons

Annual cost? Approximately $240 depending on your water quality and usage which is more than what you pay with most of the competition. At least you can join the Water for Life replacement filter program to receive replacement filters on schedule and at a 15% discounted rate.

To change the filters or membrane follow these steps:

  1. First, shut off the cold water supply underneath your kitchen sink and the tank valve. Then open the RO faucet to drain the remaining water and release pressure in the lines.
  2. Rotate the old filter(s) counterclockwise until they come loose from the manifold. Discard.
  3. Now remove the new filters from their packaging and insert them into their respective positions.
  4. At this point, you’ll want to sanitize and purge the system as described in the installation step 8 above.


Here is a link to the official manual:

NSF and Other Certifications

We have a total of 4 NSF certifications.

  • NSF Standard 42 certifies the system’s ability to remove chlorine/chloramine, particulates (Class I), and unpleasant taste and odor.
  • Standard 53 is for water contaminants with health effects. The Aquasana OptimH2O has been certified for the reduction of Asbestos, cyst, lead, mercury, MTBE, turbidity, VOCs, PFOA, and PFOS.
  • NSF Standard 58 is specifically for point-of-use reverse osmosis systems. Here, it covers arsenic 5, barium, cadmium, chromium 6, chromium 3, copper, fluoride, lead, radium 226/228, selenium, turbidity, TDS, and nitrate/nitrite reduction.
  • And finally we have NSF Standard 401 – for emerging contaminants that have found their way into our water systems in recent years. For the Aquasana RO system it covers BPA, Estrone, Ibuprofen, Naproxen, Nonylphenol, Phenytoin, Atenolol, Carbamazepine, DEET, Linuron, Meprobamate, TCEP, TCPP, and Trimethoprim.

Earlier Product Versions

The Aquasana OptimH2O has no earlier product versions as far as we are aware.

Aquasana OptimH2O Reverse Osmosis + Claryum Cons

We read about problems with leaking. The good news is Aquasana sends replacement parts free of charge.

What’s more, some people have had issues with the overall system quality. Although feeling durable enough, especially the dispenser that is part of the package seems rather flimsy. Switching back and forth between it and your regular kitchen faucet will make the difference even more noticeable.

A third con is the flow rate. It seems to be slower than what other RO systems provide.

Our biggest issue is the higher yearly maintenance cost of around $240. Even if you get 15% off when subscribing to the autoship program, it is still relatively expensive.

One more thing is that you need to anticipate a higher wastewater ratio. The Aquasana OptimH2O doesn’t use a pump so expect at least 70% of the input water to go down the drain.

Taking a look at customer reviews, while the majority were positive, there were a few outstanding issues worth mentioning. The main issue appears to be leaking from various points including the manifold, filter housings, and RO faucet. This is certainly a cause for concern and something to be aware of when considering the system. Next, the fittings are generally considered to be cheap quality, and many users had issues with these leaking as well. Lastly, a small portion of users had issues with the system generating excessive noise – although this may be related to skipping over the purging during installation.

Aquasana OptimH2O Review: Our Verdict + Best for

5 different NSF certifications for a single water filter effectively removing 88+ different contaminants – that’s hard to find. And let’s not forget that the Aquasana OptimH2O Reverse Osmosis System also adds healthy minerals to your water for optimum hydration and natural taste.

Most customers would highly recommend it, saying everything works exactly as advertised.

All that plus an affordable price tag make the Aquasana OptimH2O our #1 tank-based under sink reverse osmosis system ideal for producing clean and safe water for drinking and cooking. Our verdict: 4.5 stars!

Our Rating in Detail:

  • Filtration Performance: 5.0/5.0
  • Filter Capacity (Life): 4.5/5.0
  • Purchase Price: 4.0/5.0
  • Annual Cost: 4.0/5.0
  • Overall: 4.5/5.0

Comparison to Other Reverse Osmosis Systems

Let’s compare the Aquasana OptimH2O with two of the top point-of-use RO systems on the market right now. This should give you a better idea of how it stacks up in terms of performance and value.

Waterdrop G3 Reverse Osmosis System (G3P600)

Waterdrop G3

Price: $$$
Filter Stages: 4
Flow Rate: 0.42 gpm
NSF: 58, 372
Annually: ~$145

Overall Rating: 4.0/5.0 ⓘRating based on filtration performance, filter life, price and yearly cost, NSF testing/certification, customer support, product warranty, our testing/experience, user feedback, and other factors.

Get 10% Off! Use Code: WD10BOS

AquaTru Reverse Osmosis Water Filtration System


Price: $$$
Filter Stages: 4
Water: 1 Gallon in 10-15 Minutes
NSF: 42, 53, 58, 401, P473
Annually: ~$100-120

Overall Rating: 4.5/5.0 ⓘRating based on filtration performance, filter life, price and yearly cost, NSF testing/certification, customer support, product warranty, our testing/experience, user feedback, and other factors.

Get 15% Off! Use Code: BOSAQUATRU

Aquasana OptimH2O Reverse Osmosis System

Aquasana OptimH2O

Price: $$
Filter Stages: 4
Flow Rate Not Specified
NSF: 42, 53, 58, 401
Annually: ~$240

Overall Rating: 4.5/5.0 ⓘRating based on filtration performance, filter life, price and yearly cost, NSF testing/certification, customer support, product warranty, our testing/experience, user feedback, and other factors.

First, the Waterdrop G3 is another under sink RO system, but it uses a tankless design rather than a traditional tanked design. This design has several significant advantages, including increasing the flow rate to an impressive 0.42 gallons per minute thanks to the internal pump, which results in the system filling a standard cup of water in just 8 seconds. This may not sound particularly impressive, but it’s significantly better than typical RO systems – including the Aquasana OptimaH2O.

The pressure pump also has the bonus of reducing wastewater generation to just 33% of input water. In comparison, the Aquasana wastes 70% or more of the input water. The Waterdrop G3 also utilizes an LED smart faucet which lets you know when it’s time to change filters as well as offers real-time TDS monitoring to track filtration performance. There is no need to shut off your water when changing filters – all that’s required is a simple twist, remove, and replace.

Speaking of, the G3 system uses 4 filter stages backed by NSF testing/certification for Standards 42, 53, 58, and 401. It’s tested for the removal of chlorine (99%), VOCs (up to 99%), nitrate (98%), arsenic (99%), fluoride (99%), lead (99%), chromium 6 (99%), and PFOA/PFOS (99%) amongst few other substances.

Installation is fairly easy, and the system only uses all BPA-free materials. Waterdrop offers a 1-year manufacturer warranty when used on municipal water as well as a 30-day money-back satisfaction guarantee in case you’re not happy for any reason.

Comparing the G3 with the Aquasana system, the only major downside is its higher price point, although it should be mentioned that the annual filter replacement costs are lower at about $145 per year. Additionally, a small number of users complained of the system generating excessive noise.

Next up in our comparison is the AquaTru reverse osmosis system. Unlike the above two systems, this system utilizes a countertop design that makes it essentially installation-free. The simple, space-saving design means the system can be ready to use in just ten minutes or so.

In addition to fast filtration, the AquaTru only generates a mere 20% of input water as waste. That’s even better than the already impressive G3 system above, and significantly better than the Aquasana’s. The system also utilizes BPA and BPS-free Tritan plastic in its design.

In terms of filtration effectiveness, the AquaTru has a total of 5 certifications for standards 53, 42, 58, 401, and P473. These are the same certifications as the Aquasana but with slightly different contaminant reduction rates including 96.6% of chlorine, 97.2% of chromium 6, 87.1% of total dissolved solids (TDS), 93.5% of fluoride, 99.1% of lead, 99% of BPA, 99.99% of cysts, 96.4% of radium 226/228, 97.5% of PFOA/PFOS, as well as 86.7% to 96.6% of trace pharmaceuticals and pesticides.

When it comes to downsides, the AquaTru has some users complaining of leaking or units that stopped working after several months. Personally, we encountered no such issues. As far as cost goes, the AquaTru system costs more upfront but is less expensive to maintain on an annual basis at just $100 to $120.

All in all, our overall top pick of the above three systems is the AquaTru, due to its mix of affordable maintenance, easy installation, low wastewater generation, and NSF-backed filtration effectiveness. In second place would be the Waterdrop G3 due to its filtration effectiveness, tankless design, speedy filtration, ease of installation, and low wastewater generation. It is also our #1 tankless under sink RO system. The Aquasana comes in third place due to its lack of a pressure pump to reduce wastewater, low flow rate, and relatively high maintenance cost. It’s still our favorite tank-style under sink RO model.

This completes our review of the Aquasana OptimH2O Reverse Osmosis System. If you have any questions please don’t hesitate to leave a comment below!

About the Author Alexandra Uta

Alex is a content writer with an affinity for research and a methodical attention to detail. Since 2020, she has fully immersed herself into the home water treatment industry only to become an expert herself. Alex has been using water filters and similar products for years which has gained her lots of hands-on experience.
Learn more about .


Information provided on BOS is for educational purposes only. The products and services we review may not be right for your individual circumstances.
We adhere to strict editorial guidelines. Rest assured, the opinions expressed have not been provided, reviewed, or otherwise endorsed by our partners – they are unbiased, independent, and the author’s alone. Our licensed experts fact-check all content for accuracy. It is accurate as of the date posted and to the best of our knowledge.

Leave a Comment: