IMHO - Instead of screwing around with filtration systems and water reports, just cough up a few extra bucks when you brew and buy bottled water. Deer Park even provides a water report if you're that anal:
http://www.nestle-watersna.com/pdf/DP_BWQR_91206.pdf If you have pH concerns, I highly recommend this product:
http://www.midwestsupplies.com/products/ProdByID.aspx?ProdID=4836Water pH is very seldom discussed in homebrewing circles, but it can have a very dramatic effect on your efficiency and hop utilization.