RO Water Ph

[muledogus]

One thing I have never checked is the Ph of my brewing water or my mash. For my next batch I decided I would see what I was dealing with. I've been getting my brew water from a local "RO" water dispenser and decided to buy some cheap Ph strips from the LHBS. I tested the RO water and the Ph strips read as low as possible which was 4.6 on that scale. Of course it could be even lower if they are accurate but that was the lowest I could read. I've tested a few other household liquids and it seems like I can trust the strips to a degree. Should I try to fix this water in any way or just go buy some jugs of water from the store? My tap water is not an option as it's always either full of bacteria or full or chlorine. It was my understanding that RO water should be around neutral so what they heck is coming out of this machine? Would distilled be a better option?

 

[Yooper]

The pH is really immaterial- you want to know the alkalinity of the water. If it's indeed RO water, the alkalinity is low. The pH can be quite low, because with the removal of minerals the water can easily react with CO2 from the air. So that's not an issue at all.

My RO water is under 17 ppm of bicarbonate, so it's great for brewing. It has to do with the buffering capacity of the water and the acidic grain.

Those pH strips are not usually reliable, depending on what brand you have.

 

[Robert65]

The pH is really immaterial- you want to know the alkalinity of the water. If it's indeed RO water, the alkalinity is low. The pH can be quite low, because with the removal of minerals the water can easily react with CO2 from the air. So that's not an issue at all.

My RO water is under 17 ppm of bicarbonate, so it's great for brewing. It has to do with the buffering capacity of the water and the acidic grain.

Those pH strips are not usually reliable, depending on what brand you have.

^^^^ This.

 

[day_trippr]

[...]It was my understanding that RO water should be around neutral so what they heck is coming out of this machine? Would distilled be a better option?

It's your understanding that's amiss - and it would be even further off if you tested the pH of distilled water that's been sitting in the typical LDPE container sucking up atmospheric CO2. It's the CO2 uptake which eventually causes the pH of distilled and to a slightly lesser extent RO water to become startlingly low.

My RO system drops my ~300 TDS (~180 RA) well water down to single digits on both counts (typically 6-7 ppm, for example) and usually registers around pH 6 if measured immediately. But if I were to put a few gallons in a kettle the next morning the pH could easily be in the low 5s...

Cheers!

 

[muledogus]

Ok, don't laugh at me but I also have some test strips for my hot tub that test more. I used two different strips and it looks like, based on them that my total alkalinity is around 30-40ppm and my pH is around 6.4-6.8.

Your wealth of knowledge is still over my head at this point but I appreciate it very much. Does what I just posted seem like reasonable water to brew with?

 

[day_trippr]

Unless all of it was from iron, one could use 30-40 ppm water as the base for any style made - and make the appropriate adjustments to tune it to a specific style.
And again, pay no notice to the raw pH: there is so little ionic material in DI or RO water that the intrinsic pH is meaningless (and not infrequently difficult to even measure accurately).

As an example, I can take 12 gallons of my RO water WITH a full complement of brewing "salts" added and drop the pH from say 6 to under 5 with less than one full milliliter of 25% phosphoric acid. There's so little "stuff" in the water its pH can be shifted quite readily...

[edit] There's all kinds of great information out there for the taking wrt water and brewing. I recommend visiting https://sites.google.com/site/brunwater/water-knowledge for the education part and then grabbing a copy of the Bru'n Water program and learn how to use it...

Cheers!

 

[Yooper]

Ok, don't laugh at me but I also have some test strips for my hot tub that test more. I used two different strips and it looks like, based on them that my total alkalinity is around 30-40ppm and my pH is around 6.4-6.8.

Your wealth of knowledge is still over my head at this point but I appreciate it very much. Does what I just posted seem like reasonable water to brew with?

That alkalinity is a bit high. I would try testing again, with a cheap aquarium test kit. The kit is around $6, and measures gH (general hardness) and KH (carbonate hardness). Those are more accurate, and would give you a better indication.

My raw water has alkalinity of 228 ppm, and my RO machine drops it to under 17 ppm, according to my aquarium test kit.

 

[Silver_Is_Money]

The pH of RO water generally settles in at around 5.6 due to CO2 from the air entering it and forming carbonic acid. That said, yooper is correct in that for most source water its pH is irrelevant.

That you measure 4.6 pH via pH strips is a good indicator of their unreliability. 4.6 pH has 10 times more acidity than 5.6 pH.

 

[mabrungard]

The pH of aqueous solutions with very low ionic content (ie: distilled and RO water) is very difficult to measure. Thankfully, water pH is not really a factor with respect to brewing.