Not again!!

[Whorst]

In an effort to lower brewing costs, I'm planning on using my local tap water. I will run it through a carbon filter first. My local brewpub, which is about a mile from my house uses the local water. I consider their beers to be very good. I'm going to talk to the brewer very soon. Here's the info I have. It's very consistent from year to year. http://www.etwd.com/pdfs/Quality08.pdf

Chloride 88
Sulfate 158
Alkalinity 93
Calcium 46
Hardness 201
Magnesium 21
pH 8.2
Sodium 83

I don't know how the alkalinity or hardness is expressed. I'm going to take a guess it's expressed as CaCo3, as I've seen it on another local report listed as this. With the water being alkaline, do you think that just a 3g addition to the mash tun will be sufficient to lower the mash pH to an acceptable range? I would also add 7g to the sparge liquor as well.