Personally, I never use bottled water except for distilled water for a handful of purposes (mixing color developers from scratch and final rinses, mainly). Note that most commercial photochemicals in packets or bottles include buffering agents and other ingredients that are designed to produce consistent results with a wide range of common water issues (pH variations, etc.). As 77seriesiii says, though, it depends on your tap water, since it varies so much from one place to another.
Concerning the fixer, powdered fixers are almost always based on sodium thiosulfate. This works fine for most films, but is slower than fixers based on ammonium thiosulfate. These ammonium thiosulfate fixers are usually sold in liquid form and are usually called "rapid" fixers. TF-4, mentioned by DJGainer, is a rapid ammonium thiosulfate fixer. Rapid fixers are also usually less expensive than sodium thiosulfate fixers, on a per-roll basis. (Computing the cost can be tricky based on catalog descriptions, which are often vague about critical details like capacity.) Since the rapid fixers ship as liquids, I suppose there's a chance they'd freeze and cause a mess if they were left outside by the delivery service on a cold day. I'm not sure what the freezing point of a typical rapid fixer concentrate is, though.