Filtering Home Brewed Beer

by Brad Smith on August 27, 2010 · 35 comments

Almost all commercial brewers filter their beer to rapidly improve flavor and clarity. Yet few home brewers filter their beer, either because they lack the equipment or prefer the raw flavor of unfiltered beer. However filtering is a good option for intermediate to advanced brewers who want crystal clear, smooth flavored beer.

Why Filter?

Filtering removes yeast, tannins and some large proteins from the beer that contribute both to off flavors and haze. While many of these impurities will eventually precipitate out of the beer through lagering and aging, filtering accelerates the process by removing them in minutes instead of weeks or months. This is a big reason why commercial brewers use filters – time is money and it is much cheaper for them to filter the beer than store it for weeks or months.

Filtering also has the advantage that it can remove very small impurities from the beer – even those that would not fall out of suspension in the natural aging process. Filters can remove particles as small as 1 micron or even smaller. This can result in a cleaner flavor and much better clarity than is possible with natural aging.

A question many new brewers ask is if they can filter their beer to eliminate the sediment in the bottom of the bottles? The answer is unfortunately no, unless you have some kind of kegging/carbonation system. Filtering the beer removes the yeast from it, so if you filter and then bottle with priming sugar you will just get flat beer.

The only way to filter and bottle beer is to filter your beer into a keg, then artificially carbonate it, and then bottle it from the keg using a counter-pressure bottle filler or beer gun. Also having a pressurized keg makes it much easier to use an inline filter, as gravity works very slowly with typical beer filters.

Choosing a Filter

First, you need to choose a filter size. The filter should be fine enough to filter out tannins and yeast cells, but not too fine or it could alter the flavor of your finished beer. Around 1 micron is the sweet spot for filter size – smaller than 0.5 microns and you risk filtering out some flavor, while larger ones (5 micron and up) may leave yeast in the beer. To filter out bacteria which some commercial brewers do for shelf stability, you need to go to 0.3 microns or below. I don’t recommend going below 0.5 microns for home brewing.

Another factor when choosing filter size is how fast your filter may clog. Many commercial brewers actually use a two stage filter. They start with a 5 micron filter to eliminate the large particles and then use a smaller 0.5 micron filter inline as a second stage to filter small particles. If you have a large budget you can do the same, but for a single filter 1 micron is fine.

The most popular beer filters are inline canister filters with a replaceable filter element. These are inexpensive and work well if you have high quality filter cartridges. Some wine filters come in a plate format which offers a larger surface area that is less prone to clogging. I do not recommend using household water filters as these are slow and prone to clogging. Purchase a filter designed for use with beer and change your filter often as the small inline filters clog quickly.

Filtering Your Homebrew

Despite the fact that filtering can be used to accelerate the aging of your beer, you don’t want to filter your home brewed beer too early. Some important chemical changes take place during the later phases of fermentation and early aging. If you halt these too early by filtering you will end up with poor flavor balance. Commercial brewers use a additives and techniques that allow them to filter earlier.

Allow the beer to fully complete fermentation and then sit in the secondary for at least 2-3 weeks before filtering, then move it to your keg. The filtering process is very simple if you use two kegs. Place your inline filter in between the full and empty kegs and use low CO2 pressure to transfer the beer from one keg to the other through the filter.

Once the filtering/transfer is complete, close the top on the second keg, purge the air from the top several times and you can refrigerate and force carbonate it as you normally would with any keg.

Filtering home brewed beers is not always required or even desired, but when you want that extra bit of clarity and clean finish it is a nice alternative. Do you have thoughts or experience with filtering? Leave a comment below. Thank you for joining us on the BeerSmith Home Brewing Blog. Subscribe for more articles as well as the latest news on my upcoming brewing book and other BeerSmith products.

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{ 31 comments… read them below or add one }

Thomas August 29, 2010 at 9:29 am

When Steve Dressler of Sierra Nevada spoke at Hop Union’s Hop School he said they had stepped away from filtering that it tends to strip flavors. They are moving more towards centrifuge obviously not an option for the homebrewing environment.

I tend to think time, racking, and fining agents can get most of the same results with less work by the homebrewer. Some people will want to filter and do the extra work but I am not convinced it’s worth it.

Brad Smith August 29, 2010 at 7:35 pm

Thomas – thank you for the comments! I personally rarely filter as I find (like you) that other methods work well, and I typically have the time to properly age my beer. However it is an interesting tool for the advanced brewer.

larue August 31, 2010 at 1:27 am

you say filtering removes any remaining yeast so it’s not an option for bottles, but big breweries seem to offer a fully filtered beer in their bottles. How do they do it ?

Brad Smith August 31, 2010 at 5:57 am

Hi larue,
The large breweries will force carbonate the beer with CO2 and then use a counter-pressure bottle filler to fill the bottles while maintaining proper carbonation. Home brewers with a keg system and counter-pressure bottle filler can do the same thing. I have an article on counter-pressure fillers and beer guns here if you do a search of the BeerSmith blog.

TexHooper September 11, 2010 at 11:09 am

I am planning on getting a brewing system (might piece one together myself. I was just wondering what you would recommend for somebody that wants to keg and bottle. I have thought about using two glass carboys (one as a primary and another as a secondary fermenter). Is that worth it or not? Also, is brewers yeast needed or is regular yeast work as well?

Thanks

Brad Smith September 12, 2010 at 6:21 am

Hi – I use two glass carboys, though another popular option is the “better bottle” plastic carboys – they are less likely to break (I’ve broken two in my time). One is for the primary and one for the secondary. I would strongly recommend using liquid brewing yeast – you do not want to use “bread” yeast at all. — Brad

uwjester September 14, 2010 at 9:16 am

Thanks a bunch for the article. It really saved me on a recent ESB. I had fermented at the correct temperature and pitching rate with Nottingham, but it wouldn’t finish up or clear. I left it in the primary for 3 weeks, and the FSG was holding, so I know it was finished fermenting. Sadly, it still had a fairly good haze to it and some green-apple flavor. Even after a crash chill and letting it sit another 4 weeks, these characteristics remained. Then this article came in email and I decided I really had nothing to lose. I built up the filter, ran the beer through, and re-carbonated to recover some that came out of solution in the process. This beer is crystal clear and has a fantastic flavor now. I will probably not filter every beer I do, but this is a tool that I will definitely use again. Thanks again, and keep the articles coming.

Brad Smith September 14, 2010 at 9:38 am

Thank you! I enjoy writing the articles and in fact I will be publishing a collection of them shortly as a book on Amazon. Best wishes! — Brad

Clay September 23, 2010 at 12:42 pm

Hey-
Great article. I have recently revived my old brewing equipment and gotten back into it. I have a bit more time and patience these days so I am trying (like everybody) to find that perfect taste. I was convinced that filter would get me closer but I cold not that figure out how to do it for the reasons you mentioned above. Anyway, it’s nice to know I wasn’t the only one thinking about this.
Great site. Thanks

Glen Giddens December 11, 2010 at 8:10 am

I have a friend that’s a plumber so I got the filter cheap. I ruined five gallons of blond ale. After I ran it through the filter it tasted like liquid butterscotch. I still tried to drink it, but man I just couldn’t. It broke my heart to poor it out. I figured out what I screwed up on. When I hooked up the filter I went from the chilled uncarbonated keg through the liquid side, through the filter to the gas side of the other keg. The beer dropped to the bottom. I think I killed it with air. I should have connected the last keg to the liquid side with the pick up tube at the bottom, so the beer wouldn’t have fallen to the bottom of the keg. But one thing that was great is the beer was beautifully clear. It looked like store bought. Now that I know what I did wrong I have thought about trying it again, but pitching that other batch is making me gun shy.

Justin mclaren March 10, 2011 at 5:50 pm

Hi,
Not too sire if oxidation would have caused the beer to taste like butterscotch, sounds more like
Diacetyl to me.
I have oxidized the hell out of a beer before and although the keg only lasted a few weeks I didn’t notice any unwanted flavours.

Cheers
Justin

chris April 13, 2011 at 10:09 am

hello there, i’m from England and would like help in filtering our homebrew (brewuk.co.uk) good site,british ale/bitter.Could anyone tell me where I could purchase the filteration kit featured
on your website, is it available in usa only.
Appreciate your help, Thanks.

Brad Smith April 17, 2011 at 7:26 pm

Chris,
I don’t know many of the UK brewing shops but I bet if you posted a note on the forum (beersmith.com/forum) someone there can point you in the right direction.

Brad

Steven Richardson December 2, 2011 at 4:48 pm

I am putting together a canister beer filter like in the image show at the top of this page. My dilema is the type of filter to use, I have seen charcoal filters, poly filters and nylon filters, is there any reason not to use a charcoal filter with a finished beer?

jeff December 13, 2011 at 10:56 pm

i was thinking about the yeast removal when filtering. could it be possible to collect the filtered beer in a santizied bucket, add simple syrup and yeast, then bottle it. the simple syrup and yeast should carbonate the beer. what would u think about this technique? the only downfall i would see is having to use twice as much yeast for the entire process and the new yeast might throw off flavors in the finished beer.

Johne January 8, 2012 at 9:44 pm

I have been brewing for about 15 years, and I have been filtering for about the last 18months or so, with a filter system that looks very similar to the one pictured above. I keg, and of course, even with fining agents added near the end if the boil, there is natural sediment that finds its way down to the bottom of the keg. With the pick-up tube also at the bottom of the keg, I ended up drinking that sediment with the first round of pints. Not that a little sediment is going to kill anybody, but let’s face it, it makes the beer look goofy and it tends to impart a slightly chalky taste to the brew. I added 1 micron filter set up, and my beer is cleaner and clearer than ever before. I probably have around 50 bucks into it, and I bought it at mt local hardware store.

Mike February 15, 2012 at 12:01 pm

Johne I do the same. In fact on my last batch I used a 20 micron to filter out of the kettle….it really reduced the amount of trub in my fermenter.

Cozy March 30, 2012 at 3:47 pm

Thanks for the tips,i made a batch of beer which has a slight haze to it,ran it through a 1 micron filter system,but the haze is still there?should i use a 0.5 filter,the filter system is a clear 10″ filter with a rubber o ring at the top,a white filter but is there mean`t to be a rubber o ring at the bottom?I just popped the filter in and made sure it` didn`t leak and forced the beer under a low presure.

Charles Lashley June 24, 2012 at 11:47 am

I have been brewing since 1993. I have always used priming suger or gile in my proccess. I just filtered my first beer and I looked at a lot of sites to find out what will let a little yeast through. I ended up using a 2-7 micron plate filter hoping that a little yeast will get there. I will update you on the results in a few weeks.

Matt Watson August 19, 2012 at 4:28 am

Myself and a few mates are all new to home brewing. Have had other peoples home brews and in the past and have left with mixed feelings. A microbrewery opened up near where we live in the Mid North Coast NSW Australia. We were all hooked and bought keg fridges, but alas it went broke. Devastated with what our next step would be we have turned our hands to home brew. Remembering how its easy to leave alot of peoples home brew in the bottle, we have tried to replicate beers to flavour and clarity to what we were getting from the microbrewery. Its still a work in progress but have amazed alot of people with thinking that the beer has come from a microbrewery. I would highly recomend those who have thought about filtering to give it ago.

Scott October 11, 2012 at 12:08 am

I just filtered for the first time using a filter similar to the type at the top of this page and 1 micron cartridge. I soaked the filter cartridge in a bucket of Star San for about 10 minutes then drained for about 3 hours. When filtering, large amounts of foam were produced inside the filter housing. I poured off about the first 4 pints before attaching to the keg. It didn’t help that I was filling the keg from the IN post producing even more foam. Ok, so it’s also my first time kegging. The beer tasted fine and the pH was around 4 (safer than soda). Is this normal? Is there a better way to sanitize the filter without all the foam? Lastly, has anyone tried cleaning a 1 micron polypropylene filter to be used again?

Brad Smith October 15, 2012 at 12:01 am

When filtering it might be best to work with uncarbonated beer. You can still apply some lite pressure to it to move it around, but filtering fully carbonated beer can result in some foaming. I don’t have any great tips for sanitizing. I tend to use iodophor because it is stainless safe, and does not require a rinse, though obviously if you leave a lot of it in the filter or beer you will taste the iodine.

Matthew Linn January 21, 2013 at 3:15 pm

Cozy,

It sounds like you have a starch haze problem. Test your starch conversion with drop of iodine in the wort. If it turns a dark blue color you have unconverted starches. This happened to me on my first all grain batch. My mash temps dropped and I only mashed for 60 minutes. If I had mashed longer and tested I most likely would have been fine. Did your beer have off flavors?

I can’t wait to start filtering my batches. Just got a kegging setup and am about to buy the filter.

tom fillio May 13, 2013 at 11:33 pm

I primary ferment in 10 gallon corny kegs. I had a welder weld on 4 inch sanitary clamps for a lid, and have a blow off tube that attaches via sanitary clamps. I’m having a hard time picking up yeast and sediment from the bottom when I rack to a secondary keg via CO2. Any ideas on how to keep the yeast and sediment out. I tried cutting the dip tube 3/4 of an inch, but that didn’t completely solve the problem. Any way to fashion a filter on the end of the dip tube?

el loco July 29, 2013 at 6:30 am

Tom Fillio, the ony thing I can think of is first move the beer over to a new keg, clean keg leaving out the last few pints where the ferment is. Since you are carboninsing, you want to avoid as much as the precipitate as possible. Then from that next keg you can proceed with the carbonisation. I have to say, even when I do this I never will have ‘industrial clear’ beer, but hence filtering with something before that before adding it to the pressure tank.

el loco July 29, 2013 at 6:33 am

to add to that: it’s what 30 odd litres? Then you should leave out about a gallon (you can always use it in one more brew say, depending on how you do things), Also when I siphon between kegs, I always keep it as close to the surface as possible.

Mike September 7, 2013 at 2:40 pm

Hi there is it possible to filter my beer after it has been carbonated ?

hyspenc January 20, 2014 at 8:07 pm

hi guys
I have never filtered beer before,but got a good deal on a slightly used hand pump style filtering system
Can anyone tell me how this would work on filtering beer ,as I have a 5lt plastic keg to put the filtered beer
in and at the top is a handle to draw the beer ,in the handle is a spot to put a small co2 charge.
I have no idea how it is to be set up as the person I got it from never made beer and has no instructions so I figured
I would give it a try, I personally don’t filter my beer but would like to give it a try. thks

kale February 11, 2014 at 6:10 pm

Curious what people think about filtering an IPA. Will this strip the essential oils from the dry hopped beer?

Aljossa July 25, 2014 at 5:45 pm

Despite filtering, my beer it’s still hazy. Here is what am doing:
I’m brewing Kolsch in Speidel-Braumeister 50 liters. After transferring to conical fermentor adding Safale S-33 yeast, leaving for 3-4 days, until FG is constant, then transfer either to 30 liters Euro keg or another conical fermentor inside my cold chamber, where it is kept at temps between 3-5 Celsius (37-41 Fahrenheit) for 3-4 weeks.
Then taking that keg (beer) at that temp and push it through 10″ filter to another (also refrigerated) keg. I’ve started with 10 micron filter, no results, changed to 5 microns, nothing. Changed to 3 microns, nothing. Changed to 1 micron and again, no result. Beer seems almost absolutely the same as before filtration.
I’m not using irish moss, gelatin or anything similar, since I don’t want to add anything in my beer besides water, yeast, hops and malt.
So, what am doing wrong!?

Any thoughts appreciated!

TNX!

chandler September 22, 2014 at 9:10 am

Thank you! This article explained everything that I didn’t know/wanted to know about filtering!

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