If your tap water tastes good then it is fine for your beer. Just boil if for 15 minutes to get out the clorine and steralize it before useing it to top off a fermentor. If it doesnt taste very good then follow Ken Powers good advice about a charcoal filter for your faucet. These typically run about 20-25 dollars but are well worth the investment. If you are mashing your grains then sometimes having hard water in your area may atually benefit your extraction. I use West Jordan municiple water right from my tap with no filtration and mash my grains with great success. Sometimes bottled water has a stalr plastic taste if it is not fresh that will end up in your beer.
Before you use any water source, just make sure it tastes good to you.
Spring water is great for beer. Get a sample and boil it and taste it. Great water makes for great beer. Well coors prides itself on its water and their beer is......well......maybe thats a bad example, but for you- spring water would work just fine.