All grain water - is partial mashing a valid test?

Hi all,

I decided to postpone my dive into all grain brewing because I only had about 5-6 hours free on brew day and wasn’t sure it would be enough time. So my first AG batch has been postponed. I guess the upside to this is I can do more research and prepare more.

So, the one thing I’ve pretty much ignored until now is the topic of water chemistry and mash ph. My plan was to just use tap water in my first AG batch because I’ve done several PM batches using my tap water in the mash and the beers have turned out absolutely fantastic. Is it safe to assume that my tap water is okay to use for AG if my PMs tasted fine, or could a bigger mash and sparge result in a different mash ph and have negative effects? I could stock up on spring water if that would be safer.

Sorry if this is a dumb question. I know water chemistry is a huge topic in AG brewing and there are entire books written on it, and I’m not expecting to nail AG brewing perfectly on my first batch. Just curious if I’m on the right track or not when assuming my tap water is good enough.


If your tap water was good enough for partial mash, it should be ok for AG, unless you’re doing something off the wall for your AG. Perhaps use a Campden tablet if you have chlorine or chloramines.

What is the name of your water company/community organization that treats your water?

Thanks. There is some chlorine in my tap water so I’ll definitely pick up some campden tablets to err on the side of caution.

And looks like the organization is called The Central Lake County Joint Action Water Agency (CLCJAWA). I’m in the northwest suburbs of the Chicago area so I have Lake Michigan water. The second link here, titled “detailed water quality report 2013.pdf”, has all the details of my water supply.

It says the water PH is 7.8. Isn’t that high? I thought mash water should be like 5.0 - 5.9. But honestly, my PM batches have turned out great. That’s why I’m so eager to jump into all grain already.

That looks a lot like my water. A little on the hard side but very manageable. The only thing I don’t see on there is Chloride or Magnesium.

I wish I had your water source, mine is terrible.

My local water pH is 8.5! Sodium is 115ppm. No good to drink or brew.

Interesting. So did you modify your water at all when you brewed AG? And do you think I should make any modifications to my water, or just use a campden tab and go for it?

I wish I had your water source, mine is terrible.

My local water pH is 8.5! Sodium is 115ppm. No good to drink or brew.[/quote]

Sorry to hear that. On the upside, at least you overcame the challenge and know a lot about water chemistry now :smiley: Just out of curiosity, what water do you use when you brew? Do you buy RO water at the store and then add brewing salts?

Sorry for all the questions, guys. I’m just now starting to read up on the subject of water and I’m feeling a little overwhelmed. It’s definitely a huge topic.