ProOne Big+ Review: 6 Data-Driven Tests

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📊 Scoring Data

We conduct our own testing and use information from the manufacturer’s website and third-party test data online to compile our scoring data in our reviews. We rank a water filter’s performance with 6 factors, encompassing contaminant removal, ease of setup and use, design quality, and more. We’ve shared our scores for the ProOne Big+ across the testing categories in the table below. 

Health Related Contaminants8.71
Aesthetic Related Contaminants9.9
Performance CertificationNot certified for any reduction claims
Filtration Rate0.77 GPH
Component QualityExceptional
Component CertificationExceptional
Servicing RequirementsGood
Warranty Length5 years
ShippingFree shipping on orders over $69.95 to the lower 48 states
Returns30 days

🎬 Video Review

🚰 Contaminant Reduction

Score: 8.44

To obtain a contaminant reduction score for the ProOne Big+, we analyzed how it performed when removing contaminants from our drinking water supply, and looked for performance certifications by the NSF/ANSI, IAPMO, or the WQA. 

Our Performance Testing

The ProOne Big+ can be used to filter both treated city water and untreated water supplies. So, we conducted two separate water quality tests – one on water from our faucet and one on a river water sample we’d taken – using our preferred testing laboratory: SimpleLab’s Tap Score.

Tap Score’s sample-taking protocol is very strict, ensuring that our test results wouldn’t be compromised by incorrect practices. We started by running 100 gallons through the Big+ filters over two months to ensure they were well-used. 

To take samples, we filled a large bucket with water, and swirled it to ensure it was well mixed. We used the water to fill the ProOne Big+, then took a filtered water sample from the spigot. After, we collected the pre-filtration sample from the remaining water in the bucket. We shipped our samples to the lab for testing.

Important Note: On the Tap Score website, you can analyze your test results against your preferred water quality standards. We used Tap Score’s own HGL (Health Guideline Level), which prioritizes human health and is stricter than the federal MCLs.

Health-Related Contaminants

We assessed the ProOne Big+’s ability to remove contaminants with health effects from our city and river test water supplies. 50% of our scoring is based on the city water test results, and 50% is based on the river water test results.

Our city water testing looks at all the health-related contaminants removed by the ProOne Big+, while our river water testing focuses specifically on the filter’s ability to remove bacteria.

City Water Test:

Score: 7.30

  • Unfiltered water contained 11 contaminants with potential health effects
  • Post-filtration, ProOne Big+ effectively removed 5 contaminants
  • Disinfection byproducts (total THMs and chloroform) were only reduced by 47% and 56%
  • Some substances, like barium, sulfate, strontium, and sodium, increased post-filtration, but all remained below Health Guidance Levels

River Water Test:

Score: 10

  • ProOne Big+ effectively eliminated all three bacteria strains, manganese, and aluminum 
  • Iron and sulfate were reduced by 80% and 35%

In our city water test, our unfiltered water contained 11 contaminants with potential health effects: chloroform, total THMs, lead, copper, fluoride, aluminum, strontium, sulfate, manganese, barium, and sodium. We were the most concerned about lead and the two disinfection byproducts (chloroform and total THMs), which were detected in concentrations that exceeded the HGL. 

Brian holding the ceramic filter of Proone

Some of the possible health effects of the contaminants detected in our water include: 

  • Kidney and liver problems
  • Carcinogenic (cancer-causing) effects
  • Cardiovascular problems
  • Reproductive effects
  • Developmental and skeletal problems
  • Immune effects
  • Nervous system problems
  • Damage to the gastrointestinal system
  • Issues in the blood system 

In our post-filtration test results, we could see that the ProOne Big+ had done a good job of removing 5 of these contaminants (lead, copper, fluoride, aluminum, and manganese).

The Big+ did a surprisingly poor job of removing disinfection byproducts – total THMs were only reduced by 47%, and chloroform by 56%.

Interestingly, there were a few substances with health effects that actually increased post-filtration. Barium increased by 116%, sulfate by 69%, strontium by 56%, and sodium by 36%. Plus, bromodichloromethane – another disinfection byproduct – actually appeared post-filtration, which was surprising since we couldn’t imagine that the filter elements were introducing a disinfection byproduct into the water.

We spoke to the chemists at the lab, who said that the most likely explanation is that there were trace levels of bromodichloromethane in the influent water to begin with. However, due to its volatility, it had most likely already dissipated into the air by the time we took our pre-filtration sample.

As for the other contaminants that increased in concentration, none of these were detected above the Health Guidance Level, and in the very low trace levels that they were detected, they shouldn’t pose any risk to human health. After speaking to the lab, we think this effect is likely temporary and not an issue with any of the filters.

In our river water test, several contaminants with health effects were detected in our unfiltered water sample, including several strains of bacteria (E. Coli and Enterococcus), as well as total coliform (which gives a total reading of coliform bacteria present, including various strains), aluminum, phosphorus, sulfate, and iron.

The ProOne Big+ did an exceptional job of eliminating all three bacteria strains, awarding it top marks from us.

The filter also eliminated manganese and aluminum, reduced the iron by 80%, and the sulfate by 35%. The phosphorus concentration in our water increased, but it wasn’t found in the city water sample, which means there’s no possibility that the filters themselves introduced it to the water (and they’re not designed to remove this contaminant anyway).

Aesthetic Contaminants

City Water Test: 

  • Unfiltered water contained around 0.5 PPM of chlorine
  • ProOne Big+ effectively removed 100% of chlorine in the post-filtration test

River Water Test: 

  • ProOne Big+ performed well in removing manganese, aluminum, & iron
  • The system effectively eliminated unpleasant tastes from the water

In our city water test, we detected around 0.5 PPM of chlorine in our unfiltered water. Chlorine is volatile and dissipates quickly, so we tested for it at home with a chlorine test strip supplied by SimpleLab. 

Our post-filtration test showed that the ProOne Big+ had completely removed 100% of chlorine from our water, and we were unable to detect any chlorine tastes and odors post-filtration. This is likely down to the granular activated carbon (GAC) media used in the Big+’s filters, which the WQA describes as a “superb workhorse for water treatment”.

In our river water test, the ProOne Big+ did a good job of removing manganese, aluminum, and iron, all of which can affect water taste. We thought the ceramic shell did its job in getting rid of the suspended particles causing turbidity, and the filtered water was clear. We couldn’t detect any unpleasant dirty-water odors or tastes. 

Increase in Contaminants

A few other contaminants and impurities were detected in our city water, which don’t have known health effects, including calcium, magnesium, and chloride. The initial hardness of the pre-filtered water was 31.34 PPM, and the initial pH was 7.5.

In our post-filtered water, the concentration of calcium increased by 119%, magnesium by 261%, and chloride by 20%. This brought our water hardness up to 81 PPM, and our pH up to 8.2.

We wanted to highlight these results, but we think this is because we used a different water source to prime the filters to 100 gallons before testing, which had higher concentrations of all of these substances than the water we used for the actual test. We concluded with the lab that it’s likely a temporary effect and nothing to be concerned about.

The table below shows the contaminants removed from our city and river water samples by the Big+. 

ContaminantMeasurementPriming WaterUnfiltered City WaterPost-Filtration% ChangeUnfitered River WaterPost-Filtration% Change
E. coliPPMNDNDNDND150-100%
Total ColiformCFU/100mlNDNDNDND750-100%
Total THMsPPB0.016990.03520.01869-47%NDNDND

Performance Certifications

The ceramic and granular activated carbon (GAC) G2.0 filters used in the ProOne Big+ have been independently tested to NSF Standards 42, 53, P231, and P401, for the reduction of chlorine, lead, PFOA, microplastics, pharmaceuticals, and more. 

As of yet, the filters haven’t obtained an official performance certification for their contaminant removal abilities. 

So here, we’ve compared the contaminants removed from our water by the Big+ with the third-party testing data for these contaminants. 

Brian next to ProOne Gravity Filter

In our own testing, the ProOne Big+ did a great job of removing or greatly reducing lead, copper, fluoride, aluminum, chlorine, sulfate, and manganese.

ProOne’s third-party test data says the system can remove up to 99.9% lead, 89.8% copper, 97.5% fluoride, 98% aluminum, 84.1% strontium, 99.9% free chlorine, and 99.7% manganese, which aligned with our own test data (sulfate wasn’t highlighted in the third-party testing data).

The Big+ has also been tested to remove 84.1% strontium and 90% barium. These substances increased in our water, although as we mentioned, we think this was a one-time issue caused by the water we used to flush the filters.

But the Big+ testing data says it should remove up to 98.3% chloroform and 99.4% THMs, and the filters only removed 56% and 47% of these disinfection byproducts from our water respectively. 

The Big+ has also been tested to remove up to 99.9999% of klebsiella terrigena (a type of bacteria). While this particular strain of bacteria wasn’t present in our river water, the Big+ effectively removed the bacteria that were present.

The ProOne Big+ has been tested to remove tens of other contaminants, but these weren’t detected in our water, so we were unable to test the filter’s ability to remove them. 

We’ve compared our performance testing data with ProOne’s third-party testing in the table below. 

🚦 Filtration Rate

Score: 7.50

The ProOne Big+ is a gravity filtration system, so we knew we wouldn’t get instant access to filtered water from the unit. 

The exact flow rate for the G2.0 filters in the Big+ depends on the type and size of the filters you use. For us, with two 9-inch filters, we measured the rate of filtration at around 0.77 gallons per hour. 

We made sure to fill the top chamber first thing in the morning. That way, filtered water would always be ready in the bottom chamber whenever we needed it. 

The fact that the unit holds 3 gallons of water definitely helped us here – we had more than enough reserves for our 2-person household. Our tip is to go for the three 9-inch filters if you want the fastest access to a greater volume of filtered water. More filters = faster rate of filtration. 

📐 Design

Score: 10

We combined our notes on the quality of the ProOne Big+’s components with our data on design certifications to award the Big+ a score for design. 

As a free-standing countertop unit, the ProOne Big+ is a gravity filtration system. That means it sends water through the filters using gravity, rather than a pump or water pressure from your plumbing. 

We assembled the Big+ on our countertop in the most convenient location. It was taller than we expected, especially on the stand, so we couldn’t fit it underneath our kitchen cabinetry. 

proone unboxing

The unit has a simple design, with a top and bottom chamber that connect together, filters, and several other smaller parts, including the stainless steel spigot. When we added water to the top chamber, it would then filter down into the bottom chamber, where it could be dispensed.

The ProOne Big+ is pretty basic in design. We weren’t expecting anything super technical in the countertop gravity filtration category – our priority was contaminant removal. The unit is industrial-looking with its stainless steel exterior, and while we think it should blend in with most kitchens, it’s not a particularly attractive design.

Design Flaws & Setbacks

The ProOne Big+ has the same design flaw as other countertop stainless steel systems: if you continue to add water to the top chamber when the bottom chamber is full, water will leak out of the seal between the two chambers. 

We had to check that there was space in the bottom chamber before refilling the top chamber, which was a bit annoying – the only way to view inside the bottom chamber was to take the top chamber off. 

Component Quality

We were really pleased with the quality of the components in the ProOne Big+. Like most of its competitors, it’s made of 304 stainless steel, which means we could avoid the risk of bisphenols and microplastics leaching from plastic, and it wouldn’t shatter like glass. 

Many Big+ competitors we’ve tested use plastic spigots and other plastic components, but the Big+ is almost completely plastic-free. We only found plastic in the filter elements, which is really common – you’re unlikely to find a water filter that doesn’t use plastic elements because it’s cheap, lightweight, and easy to mold to the right shape. 

ProOne metal faucet

Design Longevity

304 stainless steel has the advantage of being more durable and having greater tensile strength than many other materials, including plastic. We couldn’t find any data to tell us exactly how long stainless steel lasts, but most sources said it has a lifespan of at least 50 years. 

We didn’t notice any signs of corrosion or rusting inside the water chambers during our testing period. 


In our research, we found that the ProOne Big+’s filter cartridges have an NSF 42 certification (they conform to material requirements only).

Note: This certification is not for performance and doesn’t mean that the Big+ has been certified to remove chlorine, taste, and odor.

Filter Materials

The filter cartridges in the ProOne Big+ are made from ceramic media with an activated carbon core

Both these materials have been proven in numerous scientific studies to be safe and effective when used for water filtration. The American Water Works Association recommends activated carbon to “solve specific water quality challenges”, and ceramic filter media is described as “suitable for point-of-use water treatment in various situations” in this 2022 study

Both activated carbon and ceramic media are usually made from natural materials, like charcoal or coconut shell (activated carbon), or clay (ceramic media). That means they’re generally non-toxic and don’t risk leaching chemicals or other synthetic materials into water. However, there’s still some plastic on the filter elements, so they’re not 100% natural.

Holding proone 2.0 cermic water filter

⚙️ Setup

Score: 8.50

We timed how long it took us to assemble the ProOne Big+, and evaluated the complexity of the setup process. 

Setup took us less than 20 minutes – the same as most of the other stainless steel countertop water filter systems we’ve tested. Alongside the filter and stainless steel chambers, the ProOne Big+ came with all the parts we needed to get it set up and start using it straight away, including a spigot and knob kit, sponge, plug, and wrench.

There were no tricky assembly jobs, and we didn’t have to prime the filters – we just ran them under cold water and scrubbed the ceramic with a scouring pad for around 2 minutes each. 

We had an easy time following the assembly instructions in the user manual. There are diagrams in the manual for visual learners, and we found a few videos online that helped show us exactly how the unit should look once assembled.

We found that setup was much easier than for Big Berkey and Waterdrop King Tank (which both need to be primed), but not quite as easy as the Alexapure Pro.

🔧 Maintenance

Score: 8.75

We also assessed the maintenance requirements for the ProOne Big+, and the ongoing spend for the filter replacements. 

Servicing Requirements

In terms of maintenance, the only task that came with a price tag was replacing the filters. The filters have a great lifespan (typically 12 months or longer), so we could simply add a reminder in our phone’s calendar for a year down the line. 

Like with the filters included in the initial purchase, the replacement filters don’t require priming aside from a quick scrub under cold water. They’re easy to screw onto the underside of the upper water chamber.

The manufacturer says you should clean the whole unit at least once a month. We preferred to clean the top and bottom chambers once a week to prevent a buildup of contaminants and generally keep things hygienic. We used hot water and soap for gentle washing, but you could use white vinegar to remove tougher stains and limescale.


We calculated that our ongoing cost per gallon for each filter in the ProOne Big+ was $0.41/gallon. This was based on the cost of the 9-inch filter (ProOne sells both 7-inch and 9-inch filters). 

This ongoing spend is pretty great compared to some of the other water filters we’ve tested. We’ve generally found that the mid-range cost-per-gallon for water filters is $0.54-0.61/gallon.

Note: Your water quality will likely affect how often you have to replace your filters, and, therefore, your personal cost per gallon for the filters you use in the Big+.

🏢 Company

Score: 8.90

Finally, we ranked ProOne as a company using combined data for its warranty, shipping policy, and returns. 


ProOne warrants its water filters for 5 years (excluding the filter elements or media) against defects in materials and workmanship under normal use and care. 

This is one of the better warranties we’ve seen for stainless steel countertop water filters. Many other manufacturers only offer 1-year product warranties.

View the product warranty on the final page of the user manual.


ProOne offers free shipping to all customers who spend at least $69.95 and who live within the US. 

The manufacturer does ship to Alaska and Hawaii, but there’s a shipping fee (the exact fee depends on the region). ProOne also ships to Canada, but notes that these orders may be “subject to duties and taxes”.


All products sold by ProOne are backed by a 30-day money-back limited guarantee, although there are a few terms: the customer must have a copy of their original purchase receipt and ship the product in its original packaging with all materials and parts. 

There’s also a shipping fee for returns, which will be subtracted from the refund amount. 

Find more information on ProOne’s shipping and returns policies here.

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  • Brian Campbell
    President & CEO, CWS, CWR

    Brian Campbell, a WQA Certified Water Specialist (CWS) and Certified Water Treatment Representative (CWR) with 5+ years of experience, helps homeowners navigate the world of water treatment. After honing his skills at Hach Company, he founded his business to empower homeowners with the knowledge and tools to achieve safe, healthy water. Brian's tested countless devices, from simple pitchers to complex systems, helping his readers find the perfect fit for their unique needs.

10 thoughts on “ProOne Big+ Review: 6 Data-Driven Tests”

  1. Avatar for Brian Campbell

    Love you work! Why do you think they have NSF accreditation for the components but not the filter capacity?

    1. Avatar for Brian Campbell
      Brian Campbell

      My hypothesis is that none of these systems (stainless steel gravity-fed units) will perform up to their claims, which is why none have achieved any third party performance certification. Whether that’s the contaminant %reduction they claim, or the capacity (gallons filtered) claims. Again, this is just a hunch, but it’s the most plausible explanation why a filter company wouldn’t get any performance certs.

  2. Avatar for Brian Campbell

    Hi, do you know if berkey filters fit in proone standing countertop ?
    I read the opposite is possible, so it would make sense, but I want to make sure.

    1. Avatar for Brian Campbell

      We’ve not tested this compatibility so can’t say for sure at this time. If you end up trying please let us know if it works for you!

    1. Avatar for Brian Campbell

      Yes it does! We lab tested one with untreated river water that had enterococcus, e.coli and coliform bacteria, and it removed 100% of all bacteria (we are working on an update to the article)

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