RO System, Good or Bad

The Homebrew Forum

Help Support The Homebrew Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Joined
Jul 1, 2021
Messages
90
Reaction score
31
I've just received this week my 5-stage reverse osmosis system, not installed as yet. I wish to use it for cooking, coffee, drinking water and brewing my lager/wine. I brew lager kits. I've been reading conflicting reports as to if is good for brewing or not. Also if using RO for brewing should one use 100% or less together with tap water. Would appreciate some help and guidance.
 
With RO water you will be starting with a blank canvas to allow you to add salts to hit the ideal balance for the beer you are brewing.
However it would be wise to understand what the salts make up is from the water coming from your tap so you can either perhaps just use tap water, mix tap water with RO water or use just RO water, all dependent on your water target for the beer type.

RO will also remove the additives put in your water by the water company, chlorine, chloramine and the like.

At the end of the day it is personal choice.

My water is hard and is generally 'Stout friendly' I'll probably be using it direct from the tap for a stout brew. However most beers I use either RO only or a 50:50 RO:tap mix.

It can be a real rabbit hole to disappear down!
 
I think as @ChilledGecko has said it really depends what you need and what you’ve got.

If you need low levels of minerals (eg brewing light lagers) and your water is high in minerals then an RO machine (or low-mineral bottled water) is good.

If you’re brewing dark beers then it’s less likely you need RO unless your water is really hard in which case you might want to blend RO and tap water to dilute the minerals.

You can do some simple tests using cheap test kits from Salifert and make a better decision when you know what you’ve got. Your water company will also publish reports about water quality - but you need to be aware these are average readings so can vary day-to-day depending on where they source the water. Most water companies have several sources with different mineral profiles.
 
Thank you gents for kindly answering my call for guidance. Brewing totally lager & wine, German, Czech, New Zealand. Will try the test but seems 100% RO may be ok. Knowing nothing about additives to the water what would you suggest I may need to add and when or how to add?
 
Did mean to display water quality result:
Calcium Hardness (mg/l)21.6
Magnesium (mg/l)1.8
Potassium (mg/l)0.8
Calcium (mg/l)18.8
Total Hardness (mg CaCO3/l)54.5
Clark English Degrees3.8
French Degrees5.5
German Degrees3.1
NI Hardness ClassificationModerately Soft
Dishwasher Setting0 - 1
 
Did mean to display water quality result:
Calcium Hardness (mg/l)21.6
Magnesium (mg/l)1.8
Potassium (mg/l)0.8
Calcium (mg/l)18.8
Total Hardness (mg CaCO3/l)54.5
Clark English Degrees3.8
French Degrees5.5
German Degrees3.1
NI Hardness ClassificationModerately Soft
Dishwasher Setting0 - 1
Oooo nice.

You could do with a little more calcium but otherwise this is pretty good water.
 
Thank you gents for kindly answering my call for guidance. Brewing totally lager & wine, German, Czech, New Zealand. Will try the test but seems 100% RO may be ok. Knowing nothing about additives to the water what would you suggest I may need to add and when or how to add?
For a regular weight of grain about a teaspoon of calcium with or before you mash the grains into the mash water, I am fortunate my mean hardness is 9.8 ppm.
Mashing is about getting your pH right 5.3 being a nice figure to aim for depending on what you are brewing.
 
Thank you gents for kindly answering my call for guidance. Brewing totally lager & wine, German, Czech, New Zealand. Will try the test but seems 100% RO may be ok. Knowing nothing about additives to the water what would you suggest I may need to add and when or how to add?
If you go 100% RO you will need to add some yeast nutrient, but as you’re brewing wine I expect you’ll have some on hand anyway.
As has been said already your water looks very good to start with. It would be worth doing an alkalinity assay to see where you are to begin with.

My tap water alkalinity is fairly high, and perfect for brown beer out of the tap. My approach is to adjust the RO dilution factor according to the style, typically 80% for pales, 50% for red and 20% for amber, so I don’t have to add acid to the mash.
 
If you go 100% RO you will need to add some yeast nutrient, but as you’re brewing wine I expect you’ll have some on hand anyway.
As has been said already your water looks very good to start with. It would be worth doing an alkalinity assay to see where you are to begin with.

My tap water alkalinity is fairly high, and perfect for brown beer out of the tap. My approach is to adjust the RO dilution factor according to the style, typically 80% for pales, 50% for red and 20% for amber, so I don’t have to add acid to the mash.
I think that is over complicating it.
For instance if using the OP's water, and hypothetically it took 1 teaspoon of chloride and a half teaspoon of gypsum to nail a pH of 5.3 using 5 kg of pale base malt, then whether making an IPA or a stout or any other beer, it will still take 1 teaspoon of chloride and half a teaspoon of gypsum to make those beers while using 5 kg of base malt.

The only malt we are trying to convert to fermentable sugars is the base malt, there is no point adding the none fermentable grains to the mash, though the none fermentables will extract a tiny portion of fermentable sugars. Makes things so much easier when playing around with brewing water chemistry.

Free up the mash tun for fermentable grains and adjuncts and either steep or add the none fermentable grains after the conversion rest.
This may be academic as far as the OP is concerned but one day he might like to brew a stout or amber ale. But one other thing I would like to point out to the OP if you prefer the continental lagers try the Hochkurz mash technique, I will be using it when I make my Bohemian Pilsner come spring.
 
With that base water profile you are pretty much set to go for any beer except possibly the lightest/softest of lagers. Just plug the numbers into something like Brewfather and add salts to get to the profile you want.
 
Thanks so much to everyone for taking the time to answer.
I brew malt extract kits, lager, no grain. I would assume I no longer need to add a campden tablet but add tsp of gypsum. Would this be all?
 
Thanks Stripejoe. Forgive me but I'm getting more confused!
😂. It’s easily done!

The changes you make to the water are to ensure your mash achieves the correct pH (if you’re brewing from extract kits you’re not doing a mash, this has all been done for you and they will have ensured the right chemistry) and to achieve the right flavour/mouthfeel (your tap water is fine for lager).

The one remaining issue with tap water is chlorination, campden tablets will fix that. 1/2 a crushed campden tablet per 30 litres of tap water dosed any time before you use it.
 
Back
Top