I would think you would want the brewing water report, although it's probably worth getting a report on each, that way you know your starting point AND how well your filtration works.
If your filter ever craps out you'll also know if/how you need to treat the tap water.
Something is always fermenting
"It's Bahl Hornin'"
AHA Summer Ale
Sonoma County Organic Cider, Wise One Wit v1.2.1, Helles Bock, Ommegang Abbey Ale Clone, Derangement (Belgian Dark Strong), Sarcastic (ESB), Kranky (Kolsch v1.1)
Alt Lang Syne (Dusseldorf Alt), 99% (Calif Common), Contentment (Trappist), Kranky (Kolsch v1.0),
Need to bottle, out of kegs!
My Site: www.restlesscellars.com