How to Use Reverse Osmosis in Brewing

Today’s post on how to use a reverse osmosis in brewing, came about due to a lot of interest people had in the mini-RO-machine in my last article.

These little workhorses (pictured below) can make around 1,200 gallons (5,455 liters) a day. However, chances are you’ll not be running the machine for a full 24 hours, to hit those numbers.

Mini RO Machines - 200 Gallons per Day - Small Brewery Equipment List

This led to a few would be brewery owners asking me about using RO (reverse osmosis) in brewing. Plus, if it was right for their planned projects.

I’m in China where most brewers opt to use a reverse osmosis machine. The water isn’t great here, with nobody drinking water from the tap/faucet.

Using an RO machine removes impurities as well as minerals and pretty much anything else from a water source. The water I treat with my RO machine, is safe to drink when it wasn’t before.

Brewers use RO machines to give them a “blank canvas”, with 99% of the impurities being removed from the water, by the units.

Starting with a Blank Canvas – How to Use Reverse Osmosis in Brewing                                                            

Throughout history brewers have been adjusting their water to make their brews “truer” to style

For example, if you want to make a Czech pilsner, you’ll look to alter your water profile to match that of the town of Pilsen in the Czech Republic. Where pilsner was first brewed.

To see water profiles from different places around the world please click here.

However, if you’re in Burton-upon-Trent, a town famous for brewing English ales. Adapting the water there, to the profile of Pilsen is difficult. As you can see below; the water profile of Burton-On-Trent is much different to Pilsen.

How to Use Reverse Osmosis in Brewing - Difference between pilsen and burton-on-trent water profiles

If a brewer has a RO machine to strip the water of the total dissolved solids (TDS). The water can be built back up to the correct mineral content required, with salt additions. For instance, to have Pilsen like water, a little addition of calcium chloride, is needed.

How to Use Reverse Osmosis in Brewing – The Science Behind the Machines

Most RO machines work the same way, with pressure being the key. Solvent (water) with solutes (minerals) flows in to a pressurized vessel, with a semi-permeable thin film membrane.

For example, the mini-RO machines pictured at the start of this post, require the feed water pressure to be 150 Psi or even higher to work properly. The pressure needed depends on the membrane used.

This membrane allows the water to pass through it, but not the dissolved solids. It’s the pressure which pushes the water through the membrane, leaving the impurities behind.

The RO Machine I Run At My Brewery In Shanghai (excuse the hole, it’s where before I arrived, they kept a CO2 cylinder)

These impurities are then flushed from the system as dirty water, usually to the drain. These RO machines remove around 99% of the dissolved solids, recovering roughly 50 to 75% of the water which passes through the machine.

It really depends how “dirty” the water is. The “dirtiness” of the water is measured in total dissolved solids (TDS) in parts per million (ppm). When using my system in Shanghai (pictured below), the water usually goes from a TDS count of around 300 to 2ppm.

The water in our brewery actually goes through a charcoal filter (to remove chlorine) and a sand filter, before entering our RO machine. The treated water is stored in a tank for use when needed, in the brewery.

How to Use Reverse Osmosis in Brewing – A Basic RO Set-up

Here, I’m going to explain what a basic RO setup looks like. Which is sufficient for most breweries. It’s the same set-up I have at the brewery I’m currently in Shanghai.

Some brewers will suggest different setup having a reason for it. Here’s though I’ve put together a diagram, to show a typical brewery RO system.

How to Use Reverse Osmosis in Brewing - Typical RO Water Setup in a Brewery

Now in this setup above, if the water pressure isn’t sufficient from the mains. You may need another reserve tanks filled with untreated mains water. This reserve tank like the treated RO vessel in the diagram above, has an on-demand water pump.

This pump will automatically begin pumping water to the RO machine when needed. It’s as simple as turning on the machine; which opens a valve, automatically turning the reserve water pump on.

What If You Don’t Have any Pre-treatment?

If you don’t have pre-treatment like the charcoal and sand filter above, the brewery needs a bigger RO machine, as there’s more processing to do.

So, the untreated water first passes through a sand filter which catches things like small particles, sand and grit. It then goes through a charcoal filter which removes some organisms, reduces chlorine, pesticides, solvents and other stuff.

This water will still have dissolved solids like calcium, nitrates and fluorides in it. This is where the RO machine comes to the rescue, removing 99% of these impurities and minerals giving the brewer a “blank canvas”. Which they can build back up with brewing salts, to produce a beer truer to style.

How to Use Reverse Osmosis in Brewing – There Are Some Downsides

There are some downsides to using an RO machine. There’s cost to running the machine using electrical power. An RO machine will take up valuable floor space in a brewery too.

Plus, as we’ve said before, there’s waste water which goes to the drain. Depending on the water source and how “clean” it is, you can end up with as much wastewater as treated water.

Typically, an RO machine recovers between 50 and 75% of the water which flows through it. If the water you’re treating is dirty, with a high concentration of dissolved solids, a lot of wastewater will be produced.

This is why I’d always recommend some form of pretreatment, such as the sand and charcoal filters pictured below, which I’m using now.

How to Use Reverse Osmosis in Brewing - Sand and Charcoal Filters

Yes, there is a bigger upfront cost but you’ll waste less in the long run, as the water treated by the machine will be much cleaner.

The Advantages of Using RO Water – How to Use Reverse Osmosis in Brewing

Even with the downsides listed above; RO water is a prudent choice for brewers wanting greater control over the beers they produce.

There are only four main ingredients in beer so, having full control over one of them (the water), is always going to make the beer brewed, better.

For example, in another article on this site, we discuss how the chloride to sulfate ratio of brewing water effects the refined bitterness of a beer. Knowing your water will be consistent every time using an RO machine, means hitting mash pH is much easier too.

Did you know mains water often comes from many sources? Throughout the year local authorities can switch where you water comes from. Without an RO machine, you’re brewing water can be wildly different, from one month to the next.

It means the water needs analyzing regularly in the brewery to ensure the water additions are still correct. Having an RO machine allows a brewer freedom from the constraints of geography and local water chemistry.

Whether brewing a German Pilsner of dry stout; it doesn’t matter if you begin with a blank canvas and then build the water back up with the correct salt additions.

Running an RO Machine

Running most RO machines is easy enough. They pretty much look after themselves. For instance, the machine I’m currently running, the only real maintenance is replacing the PP (polypropylene) filter cartridges every 3-months or so.

If the water entering the RO machine is lower than 500ppm (parts per million), then changing the PP filters every 3-months is enough. Obviously at the same time you’re changing the filters, ensure the inside of the filter housing is cleaned too.

How to Use Reverse Osmosis in Brewing - PP filters
These are the PP filters for my RO machine

If the water is dirtier (above 500ppm), then I have to change the filters more often. In reality, I do a visual check every month, to see how dirty the cartridge PP filters are.

On a day-to-day basis when I run the machine, I need to check the two floats (pictured below – ringed in red) are balanced (at the same level). Which is simple as turning the valve (ringed in blue), to adjust the flows.

How to Use Reverse Osmosis in Brewing - Keep The Floats Balanced Ringed

Otherwise, the only other concern, is ensuring the untreated mains water tank feeding the RO machine doesn’t run dry. Other RO systems may have more actions needed for preventative maintenance; it really depends on the system.

However, in general as I said before, they kind of look after themselves. And there you go; we’ve covered the main aspects RO water use and running an RO machine in a brewery.

How to Use Reverse Osmosis in Brewing Conclusions

I hope our post today on how to use reverse osmosis in brewing has proved useful.

As I say this article came together when people started reaching out. Asking about the mini-RO machines pictured at the start of the post, which can treat 1,200 gallons of water per day. The unit price is US$ 1,250.

I often have people enquiring about RO machines pricing, of units made in China. As in many other countries units are harder to source, and much more expensive to buy.

I like having an RO machine. It provides a blank canvas from which to build the water back up, with the correct salt additions. Allowing me to make a beer truer to style.

Calcium Carbonate Brewing Salts
Calcium Carbonate – A Brewing Salt Often Used in Brewing

However, I always advise clients to get their water analyzed first, as in some places an RO machine isn’t needed.

For example, when I brewed in Yerevan, Armenia we didn’t need an RO machine. As the water was similar to that of Pilsen, being low in mineral content.

If you have any feedback or follow-up questions then please feel free to contact me at:

I can also assist with other brewing projects you may have…
  • Be it sourcing equipment
  • Recipe formulation
  • Improvements in processes in the brewhouse

I’ve over 25-years brewing experience operating breweries around the world, from brewpubs to productions breweries. So, if you’ve any questions give me a shout.

As you can also contact me directly on your favorite platform by scanning the relevant QR code below, adding me and messaging me directly.

For now, thanks for reading, have a great day and happy brewing.

Neil Playfoot

Neil is a brewer with 25 years international brewing experience. Based out of China (first came in 2010) he works as a brewing consultant helping brewers with their projects and brewing processes. To find out what services Neil can provide your brewery please click here. If you'd like to contact Neil you can email at
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