Review: ZeroWater 32-Cup Ready-Read Countertop Water Filter Dispenser

Full Analysis of the ZeroWater 32-Cup

Filtration: 4.31/5.00

In our analysis, the ZeroWater 32-Cup achieved a filtration score of 4.31/5.00, the best among all non-RO countertop water filters we’ve tested up to this point.

In summary, we’ve lab-tested the filter element used by the ZeroWater 32-Cup twice – once in the 32-cup dispenser itself and once using a fresh cartridge in the ZeroWater 10-Cup Ready-Pour Pitcher – and both times it achieved exceptional reduction rates for most undesirable impurities. However, we found problems with potential copper leaching and lackluster reduction of chloroform. Taste and odor of the filtered water were flawless, and although missing most organics, the system is backed by a few important NSF certifications for contaminant reduction + additional testing against NSF and other standards.

1. Lab Results: 4.81/5.00

In our second round of lab testing the ZeroWater filter element (installed in the ZeroWater 32-Cup dispenser) which we conducted as part of our countertop water filter comparison, it could remove all undesirable tap water impurities to below the minimum detection level except:

• Chloroform, which wasn’t reduced at all. In fact, the lab measured a 95% concentration increase in the filtered water. However, we think this is just natural fluctuation and highly doubt that the ZeroWater leached any chloroform into our water. Anyway, 2 other testers got similar results independently from us: The EWG (82% average reduction of disinfection byproducts) and Modern Castle (~40% reduction of chloroform). The problem with lackluster filtration of chloroform/disinfection byproducts (or maybe even organic compounds in general) is that they are highly abundant in tap water often exceeding their strictest health guidelines and associated with adverse health effects such as bladder cancer.
• Fluoride, which was reduced by at least 75% which is outstanding.

In our first round of lab testing the ZeroWater filter element (installed in the ZeroWater 10-Cup Ready-Pour Pitcher) which we had conducted as part of our water filter pitcher comparison, it could remove all undesirable tap water impurities to below the minimum detection level except copper, boron, and fluoride.

• For copper we saw a 1,100% concentration increase from 0.01 to 0.12 ppm. We think the ZeroWater filter element might have leached some of its KDF media which is a mixture of copper and zinc. This leaching isn’t ideal, but at 40% of the strictest health guideline for copper in drinking water we could find, we are also not overly concerned.
• For boron we saw a 75% reduction so not perfect but still solid.
• And for fluoride we saw a minimum reduction rate of 78% so yet again really outstanding (although it might be possible that the fluoride reduction results from our pitcher comparison are flawed).

And finally, for our first round of testing there was a tiny amount of aluminum detected in the filtered water which hadn’t been detected in the raw water sample. However, this might just be coincidence and even if not, the detected level of 0.01 ppm was 60 times below the strictest aluminum health guideline (0.6 ppm) we could find, so nothing to worry about.

And by the way, in both rounds of testing we did see a TDS reduction in our water close to 100% as claimed by ZeroWater. But we don’t like this TDS focus for 2 reasons:

1. The vast majority of dissolved solids in tap water are usually healthy minerals like sodium, magnesium, potassium, and chloride. Removing these doesn’t provide any health benefit, unless maybe if you are suffering from kidney stones or a similar condition.
2. Many people seem to believe that 0 TDS water is always free from undesirable impurities which is not true. TDS completely ignores undissolved substances floating in water, some of which can be potentially harmful such as VOCs and particulate lead.

In other words, TDS is not a good measurement to determine drinking water quality unless TDS levels get really high, above 500 or 1,000 which may indicate potentially harmful contamination, and the sheer amount of dissolved solids likely results in unpleasant water taste and/or appearance, so aesthetic issues. But a TDS level anywhere between 0 and 500, can be perfectly fine, provided that it’s made up of healthy minerals and stuff like that.

Lab Results Chart for Testing of the ZeroWater 32-Cup Ready-Read Dispenser

*100% means reduction to below the minimum detection level. To learn more about our testing procedures check our editorial guidelines.

Link to Filtered Water Report
Link to Unfiltered Water Report

Lab Results Chart for Testing of the ZeroWater 10-Cup Ready-Pour Pitcher

*100% means reduction to below the minimum detection level. To learn more about our testing procedures check our editorial guidelines.

Link to Filtered Water Report
Link to Unfiltered Water Report

2. NSF Certifications and Other Test Data

The ZeroWater 32-Cup is certified for contaminant reduction by the IAPMO against NSF standards 42 and 53, and by the NSF against standards 42 and 53. We counted 7 analytes covered including lead (95.9-99.7%), PFOA/PFOS (94.9%), and chromium 6 (99.6%). Especially chromium 6 is very rare for any non-RO water filter so this is great (check the official performance data sheet here)!

ZeroWater also provides additional in-house contaminant reduction test data with some of the testing conducted against NSF standards 42 and 53 and for the full filter life. The results look good although they’re mostly limited to metals and salts and we miss reduction rates for most organic compounds.

3. Filtration Process

The ZeroWater 32-Cup combines several different filter layers and materials in a single cartridge. Based on the official ZeroWater website we’re not 100% sure about the exact composition, but it should be very close to this:

• First comes a mesh filter screen to block sediment and other larger particles.
• Next comes a foam distributor to evenly distribute the water across the entire filter diameter.
• Granular activated carbon is used to remove organic compounds. According to the zerowater.com FAQ section, the carbon is mixed with KDF filter media probably to stop bacteria from accumulating.
• Second to last comes a mixed bed of ion exchange resin. It’s a mixed bed for trapping both positive and negative ions (cation and anion resin bed). This absorbs all kinds of inorganic compounds such as metals and salts.
• And finally, we have a fine mesh screen which removes finer particles and prevents filter media from escaping the cartridge.

4. Taste and Odor Test

In our test, the freshly filtered water provided by the ZeroWater 32-Cup tasted and smelled perfectly clean.

Usability: 4.50/5.00

The ZeroWater 32-Cup Ready-Read Dispenser is easy to set up, use, and maintain. But, the plastic handle used to dispense water seems a bit small. In our speed test, the system could filter and dispense 12 ounces within 3:02 minutes which should be fast enough for regular use. There’s no filter life indicator but a TDS meter which you’re supposed to use to determine the ideal time to replace filters (once the meter reads “006” or higher). In our opinion, there’s pros and cons to this approach (more info below).

1. Initial Setup

Setting up the ZeroWater 32-Cup is a simple process that doesn’t take very long:

1. Remove the blue cap from the filter cartridge.
2. Clean all dispenser components that will touch water using soapy water.
3. Rinse the exterior of the filter cartridge with warm water for 30 seconds.
4. Twist the filter cartridge into the bottom of the reservoir. Tighten to ensure a complete seal.
5. Wet the blue O-ring of the spigot. Then push the spigot into the hole until you hear a click.
6. Filter and discard the first 2 reservoirs of water.
7. Place the TDS meter into the spigot.

2. Everyday Use

Once set up, the ZeroWater 32-Cup dispenser is very easy to use: You simply remove the lid, fill the upper reservoir, put the lid back on, and wait for the water to filter through which, based on our speed test, should take around 6 minutes so not very long. Then you can dispense water by pulling down the plastic handle (which feels a bit small).

While dispensing water you can also turn on the TDS meter docked to the spigot. This gives you an instant TDS reading.

3. Filtration/Dispensing Speed Test

In our speed test, the ZeroWater 32-Cup could filter and dispense 12 ounces of water within 3:02 minutes. For this test we filled the upper reservoir to the top.

4. Maintenance (Filter Replacements)

Replacing the filter cartridge is straightforward and self-explanatory:

1. Unscrew the old filter cartridge from the bottom of the reservoir.
2. Remove the blue cap from the new filter cartridge.
3. Rinse the exterior of the filter cartridge with warm water for 30 seconds.
4. Twist the new filter cartridge into the bottom of the reservoir. Tighten to ensure a complete seal.

Each filter is rated at 15 to 17 gallons. But there is no filter life indicator. Instead, there is a TDS meter included in the package which you’re supposed to use to determine the ideal time to replace filters (once the meter reads “006” or higher). In our opinion, there’re pros and cons to this approach: On the one hand, you’re replacing filters based on your actual water quality whereas filter life indicators work based on predefined parameters which may or may not fit your water conditions. On the other hand, TDS is not a good measurement to determine water quality as explained above.

Costs: 2.00/5.00

1. Upfront Price

As of Jan 20, 2025, the regular price tag for the ZeroWater 32-Cup is $44.99 which is pretty average for this type of countertop filter.

2. Long-Term Expenses for Filter Replacements

Provided you replace filters based on their rated life of only 15 to 17 gallons, you’ll spend anywhere between $380 and $430 a year – much more compared to the direct competition! – if you consume 500 gallons of filtered water.

Additional Ranking Factors

1. Space-Saving Design

The ZeroWater 32-Cup has a slim and space-saving design.

2. Plastic Reservoir

The plastic reservoir feels like it could be prone to cracking.

3. Warranty

There’s only a very short 90-day warranty.

4. Frequent Customer Complaints

Checking third-party customer complaints, we read about taste/odor issues, slow filtration and clogged filters, leaking filters, and faulty TDS meters.

Bottom Line: The Best/Most Effective Regular Countertop Water Filter

The ZeroWater 32-Cup Ready-Read Dispenser scores a final rating of 3.89 out of 5.00.

Together with the Aquasana Clean Water Machine, we consider it the best and most effective regular countertop water filter we’ve tested so far. Most importantly, the ZeroWater 32-Cup holds a few important NSF certifications for contaminant reduction and it’s backed by additional (NSF) testing, although we miss certification/testing for organic compounds. In our 2 rounds of lab testing the filter element we saw 100% reduction of most undesirable impurities. Taste and odor of the filtered water was perfect, too. We also like the system in terms of usability (except for the small plastic handle) and filtration speed. Finally, we have a slim, space-saving design and affordable upfront cost.

What we don’t like is the “0 TDS approach” which seems to confuse a lot of people. What’s more, the ZeroWater filter element might have problems filtering chloroform or disinfection byproducts or even organic compounds in general. And in our first round of lab testing we detected a higher level of copper in the filtered water. Last but not least, the plastic reservoir feels a bit thin and prone to cracking, the extremely short filter life means frequent replacements required and very high annual cost, we only have a short 90-day warranty, and third-party customers complained about taste/odor issues, slow filtration and clogged filters, leaking filters, and faulty TDS meters.