Distilled water PH

[smarch0]

I looked around and can't seem to find a clear answer. I moved recently and am now on a well and will be using distilled water going forward. I am wondering what people are entering in their given water calculators for the PH of distilled water. A general internet search is saying anywhere from 5.8 to 7, so what should I be using?

 

[h22lude]

Water pH isn't important for mash pH. Enter the other information and you will be fine. If it requires a pH, use 7

 

[NTexBrewer]

A pH meter will solve your problem...

Without a meter if you are using a water build program enter your pH as 5.8, 6 and then 7 and I bet you will not see much difference in your final numbers since distilled water has no residual alkalinity.

If it is not too cost prohibitive, I would get your well water tested. You may find that your water is ideal for most brewing styles or doing 50/50 distilled/Well Water

 

[Vale71]

Water PH is immaterial and is not even used in mash PH calculations. Why some calculators ask you to enter a value for it will forever remain a mystery. Just enter whatever number you like and see the numbers not change one little bit...

 

[dmtaylor]

The pH of distilled water cannot be accurately measured with the instruments used by homebrewers. In real life it is slightly lower than 7 because carbon dioxide will dissolve and turn into carbonic acid, so it is likely in the range that you have found, probably in the 6's. Try entering 6.5, that's a close approximation.

I tend to agree with @Vale71 as well, insomuch as the pH of the raw water doesn't matter anywhere near as much as the pH of the mash, after it is combined with the malt.

A simple mash of standard pale brewer's malt in distilled water should give a pH of about 5.8 on average. Many specialty grains including any/all crystal malts and dark roasted grains will reduce mash pH by about 0.03 for every 1% of the total grist. It's a great rule of thumb that I use in designing every recipe. Source: Designing Great Beers by Ray Daniels. And my own 160+ batches of experience matches Ray's findings very well indeed.

And what should be your goal for mash pH? For optimum enzymatic action, should be 5.45-5.65 as measured at room temperature, which equates to the oft-cited range of about 5.2-5.4, which based on a zillion sources I won't mention was always intended to be the range as measured not at room temperature but at MASH temperature. This is a FACT which many/most homebrewers love to argue about, but doesn't change the fact that it's a fact.



Cheers all.

 

[1HW]

Distilled water has nothing to buffer against swings in pH, and as @dmtaylor said, when distilled water comes in contact with CO2, the pH will decrease. The important piece, as others also note, is building a water profile that will result in a 5.2-5.6 pH mash.

 

[smarch0]

Great, thank you all for your response! I know just enough to get me into trouble, and this helps dig me out of some of that trouble

 

[RolandD]

Pure distilled water is neutral pH, 7.0 It is the basis for the whole pH scale. As others have noted, it will absorb CO2 and become, very slightly, acidic.

 

[day_trippr]

Not so slightly, as I've measured it as low as 5.8. Those ldpe jugs are wicked gas permeable.
But has been said repeatedly, it doesn't matter wrt brewing as the buffering capacity is zero...

Cheers!

 

[1HW]

Pure distilled water is neutral pH, 7.0 It is the basis for the whole pH scale. As others have noted, it will absorb CO2 and become, very slightly, acidic.

Not so slightly, as I've measured it as low as 5.8. Those ldpe jugs are wicked gas permeable.
But has been said repeatedly, it doesn't matter wrt brewing as the buffering capacity is zero...

Agreed, pure distilled water (or RODI water) begins its life as neutral 7.0 pH. The problem is that it will not measure as such with a pH meter because 1) distilled/RODI water has no buffering capacity, and 2) when exposed to CO2, the unbuffered water will acidify. The pH swing can be considerable as @day_trippr notes.

The challenge for new brewers and/or non-chemists is that our knowledge base stops at "Distilled water pH = 7.0". Then when someone measures their distilled water with their spiffy new Milwaukee pH meter and it reads 5.8. or 6.2, or 6.5 for 3 seconds only to move to 5.9 a second later, they panic and curse their meter or the distilled water. And so it's important to note that this is normal, and as others note, to focus on the target mash pH, not the moment-to-moment pH of the distilled water source.

 

[Vale71]

Agreed, pure distilled water (or RODI water) begins its life as neutral 7.0 pH.

Even that is not really true. RO membranes play havoc with ions, including OH- and H3O+ so the actual result is quite unpredictable, depending on membrane, temperature, pressure and whatnot. It would take time for the water's PH to actually drift back to 7.0 but by then it will be already saturated with CO2 from the atmosphere.

 

[Mikey B]

Ahh pH.
DI or RO water is very difficult to measure pH and it is correct that until you add ions it is a moot point. It has no buffering capacity. Think of it as a blank canvas. Make something awesome or at least what you like!

 

[VikeMan]

Water PH is immaterial and is not even used in mash PH calculations. Why some calculators ask you to enter a value for it will forever remain a mystery. Just enter whatever number you like and see the numbers not change one little bit...

Some models use it to calculate carbonate species from total alkalinity or vice versa.