The quality of water used in brewing is important to the flavor of the finished beer. Most home tap water, especially if you live in a city, can have an objectionable chlorine or "re-used" flavor. Some rural water also has un-wanted flavors which can include chlorine from purification systems and sulfurous "rotten-egg" odors. Some of these can be filtered and used in the boil. For the remainder of the wort volume, though, you should use a bottled "spring" water. Harder water tends to hold grain and hop flavors better than soft water, which, if artificially softened, can be too salty. Popular brew books suggest the amount of hardness and even tell how to adjust it. I use my hard, filtered well water for the boiling wort (3 gallons) and fill the remainder of the carboy with water I have boiled and cooled the night before, stored in sanitized containers, saving about $8 a batch.
Good beer kits for almost any style of beer are available all over and run around $30 for the ingredients to make a 5 gallon batch (about 48 bottles). Most towns of any size have homebrew outlets that either stock ingredients or put together kits for a few popular types of ales. Check your phonebook under "beer: brewing supplies".
Click on the image at right to see a breakdown of an excellent Pacific Porter kit from Hermann's Homebrew of Central Point, Oregon.
On the Web: Just do a Google search for "hombrew kits" or try these:
Useful Printed References: