ProOne Big+ Gravity Water Filter

The gravity water filter market changed in 2023 when Berkey lost its EPA registration and faced a series of regulatory challenges. Longtime Berkey loyalists suddenly needed a backup plan. ProOne stepped into that gap with the Big+, a stainless steel gravity filter that looks like a Berkey, functions like a Berkey, and comes with something Berkey struggled to provide in its final years: independently certified lab testing with published results.

I have been running a ProOne Big+ alongside my Big Berkey for three months. Here is what I found when I stopped trusting brand loyalty and started trusting data.

Why People Left Berkey

Before I talk about the ProOne, the context matters. Berkey was the dominant name in gravity water filtration for over two decades. It built a devoted following among the off-grid, prepper, and health-conscious communities. But in recent years, Berkey faced several issues that eroded trust.

The EPA registration lapse meant Berkey could no longer legally sell its filters as pesticide devices (which is how the EPA classifies water purifiers that claim to remove bacteria and other biological contaminants). Independent testing by third parties raised questions about whether the Black Berkey filters consistently met their advertised contaminant reduction claims. And Berkey’s response to these issues was slow and often opaque.

None of this means every Berkey filter is dangerous. But it means the company that once owned the gravity filter market lost the trust of a significant portion of its customer base. ProOne positioned the Big+ directly in that trust gap.

What the ProOne Big+ Offers

The Big+ is a 2.75-gallon stainless steel gravity filter with two ProOne G2.0 filter elements. The design will look immediately familiar to anyone who has used a Berkey: an upper chamber where you pour unfiltered water, two filter elements that water passes through by gravity, and a lower chamber where filtered water collects with a spigot for dispensing.

The stainless steel construction is 304-grade, the same as Berkey uses. Build quality is comparable. The chambers nest together for storage, the spigot threads are standard, and the rubber blocking plugs for unused filter holes are identical in function. If you have used a Berkey, you can set up a ProOne Big+ in five minutes with zero learning curve.

The key difference is the G2.0 filter elements. ProOne’s filters are independently tested by Envirotek Laboratories and certified to NSF/ANSI 42, 53, and 401 standards. The published test results show reduction of over 200 contaminants, including fluoride (95%), lead (99.9%), chlorine (99.9%), pharmaceuticals, pesticides, and volatile organic compounds. ProOne publishes the full lab reports on their website. You can download the PDFs and read the actual test data, which is more transparency than Berkey provided in its later years.

Flow Rate Comparison

I ran a controlled flow rate test: upper chambers filled to the same level at the same time, both with two filter elements, using the same municipal tap water source.

ProOne Big+ with two G2.0 elements: Filtered 2.75 gallons in approximately 3 hours and 15 minutes for a freshly primed set of filters. After two months of daily use, flow rate slowed to approximately 3 hours and 45 minutes for the same volume.

Big Berkey with two Black Berkey elements: Filtered 2.25 gallons (its smaller capacity) in approximately 2 hours and 30 minutes with broken-in filters. Proportionally, the Berkey filters slightly faster per gallon.

The flow rate difference is noticeable but not dramatic. The ProOne is about 15 to 20 percent slower than the Berkey on a per-gallon basis. In daily use, this means you fill the upper chamber before bed and wake up to a full lower chamber either way. If you are filtering water for a large family and refilling multiple times a day, the slower flow rate adds up. For one to four people, it is a non-issue.

Taste and Water Quality

Both the ProOne and the Berkey produce excellent-tasting water. I ran a blind taste test with four people in my household. Nobody could consistently distinguish between ProOne-filtered and Berkey-filtered water. Both removed the chlorine taste from our municipal supply completely. Both produced clear, clean water with no sediment or off-flavors.

I tested the filtered water from both systems with a TDS meter. The ProOne reduced TDS from 340 ppm (our tap water baseline) to approximately 290 ppm. The Berkey reduced TDS from 340 to approximately 300 ppm. These numbers are consistent with activated carbon filtration, which removes contaminants but does not strip all dissolved minerals the way reverse osmosis does. That is actually a feature: you want some minerals in your drinking water.

Filter Longevity and Cost

ProOne rates the G2.0 elements for 1,200 gallons each. With two elements and a household using approximately 3 gallons per day, that works out to about 800 days or roughly 2.2 years before replacement. Replacement G2.0 elements cost approximately $55 each or $110 for a pair.

For comparison, Black Berkey elements are rated for 3,000 gallons each, which sounds dramatically better. However, the Berkey rating assumes laboratory conditions and consistent maintenance. Many users report Black Berkey elements slowing significantly before reaching 3,000 gallons, especially in areas with harder water. Real-world longevity for Berkey elements tends to land between 1,500 and 2,000 gallons in my experience. Replacement Black Berkey elements cost approximately $60 each or $120 for a pair, when you can find them in stock.

On a cost-per-gallon basis, the two are remarkably close. ProOne runs approximately 4.6 cents per gallon. Berkey, assuming real-world element life, runs approximately 3 to 4 cents per gallon. The difference over a year of daily use is less than $10.

Price Comparison

ProOne Big+ (2.75 gallon, two G2.0 elements included): approximately $295.

Big Berkey (2.25 gallon, two Black Berkey elements included): approximately $320 when available through authorized dealers, though prices vary significantly depending on availability.

The ProOne costs less upfront, includes a larger reservoir, and comes with two filter elements included. The Berkey commands a premium based on brand recognition and legacy reputation.

Build and Design Nitpicks

The ProOne Big+ is not without flaws. The spigot is functional but feels slightly cheaper than the Berkey’s. The upper chamber does not seat as snugly on the lower chamber as the Berkey, leading to occasional wobble. The instructions could be clearer about priming the filter elements, which involves running water through them under pressure for about 60 seconds each. Experienced gravity filter users will know the drill. First-timers might find the priming process confusing based on the included documentation.

The lid fits well and includes a hole for filling without removing it, which is a thoughtful design touch. The overall footprint is similar to the Big Berkey, and it looks nearly identical on a kitchen counter. Most visitors to my house have not noticed that I switched.

Who Should Buy the ProOne Big+

Buy it if you want a gravity water filter with independently certified performance testing and transparent lab results. The ProOne Big+ delivers the same daily experience as a Berkey — excellent-tasting filtered water from a stainless steel countertop system — with stronger documentation of what it actually removes. If you left Berkey due to the EPA and certification issues, ProOne directly addresses those concerns.

Skip it if you need the fastest possible flow rate for a large household (consider the ProOne Traveler for its higher element-to-volume ratio, or look at pressurized systems), or if your water source has extremely high sediment that could clog the G2.0 elements faster than rated.

The Bottom Line

The ProOne Big+ is what many Berkey owners wished Berkey would become: a gravity filter with the same stainless steel build quality, the same countertop convenience, and the same excellent filtration, but with certified lab testing and transparent documentation to back up the claims. It costs less, holds more water, and does not carry the regulatory baggage that now follows the Berkey name. For off-grid homes, emergency preparedness kits, and everyday kitchen use, the ProOne Big+ earns its position as the gravity filter I recommend in 2026.