I am getting ready for my first all-grain batch. I got a copy of my township's water report and sat down to use it in conjunction with the graphs in How to Brew to determine what colors of beer I can make without pH adjustments and if I want to make other beers, what adjustments I need to make. The problem is the water report doesn't list the Magnesium content. This data is crucial to using the charts. I've emailed my township to try to get the info, but I'm not sure I'll hear back.

Assuming I don't know the Mg content of my water and thus can't predict my mash pH, can I just measure the pH of the mash using a pH meter and adjust accordingly? Is taking a measurement actually better than estimating based on the water report? When should I take the measurement - after doughing in? After X minutes?

According to How to Brew, brewing water is adjusted with salts before you begin mashing. If I can't predict my mash pH and instead have to measure it after starting the mash, how should I add the adjusting salts? Should I mix them into a pint or so of water then stir them into the mash as well as I can? If so, should I consider the start of the mash timer to be when I've adjusted the pH?2.

  • I'll just be doing a single-step infusion mash in a picnic cooler MLT, if it matters.
    – JackSmith
    Dec 29, 2010 at 17:07
  • Personally, I'd wait to get into water chemistry until I had a few batches under my belt, unless you suspect there to be problems with your water source. It's a giant can of worms that you may wish to hold off on for your first all grain batch. There are so many other things to worry about, and you'll be left wondering if your changes to the water affected the outcome in good or bad ways. That said, if you feel like you have a good handle on the elements involved in adjusting the water chemistry, by all means have at it. Just saying that personally I'd hold off on it.
    – markskar
    Jan 3, 2011 at 16:52
  • @markskar: Thanks for the comment. My water is pretty run-of-the-mill, meaning it lends itself well to brewing amber beers without adjustment. My plan is to brew an amber with the water as it is, then later try some very dark and very light beers where I'll need to adjust the water. Even if I don't need to adjust for the first batch, eventually I'll need to so I'm thinking about it now...
    – JackSmith
    Jan 4, 2011 at 0:13

1 Answer 1


There are 2 reasons to adjust your water...to get the proper pH and to add minerals necessary for yeast health and beer flavor. To do the former, you can simply measure the pH with a meter or papers, then empirically add salts until you achieve the desired pH. You don't pretreat the water because it's the mash pH you're concerned with, not the water pH. In addition, many salts will not dissolve in water and must be added to the mash. Wait about 5 min. after mashing in, them check the pH. But really, you should have a decent water report before you start messing with water chemistry. If you can't get one form your township, a great source it www.wardlab.com. Get test W-6 for $16.50 and it will tell you everything you need to know about your water. Keep in mind that depending on what buffers are already in your water, different types of additions may produce different results. That's why a complete water report is so important. With a water report, you'll not only have info you need to treat pH effectively, but you'll also be aware of mineral profiles that can affect the flavor of your beer.

  • Sorry for the double post...I got logged in under another username.
    – Denny Conn
    Dec 29, 2010 at 18:38

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