Epinions: Water Filters and Purifiers
Consumer-generated reviews, buying tips and advice, ratings, price information, and searchable in a variety of ways from price to product type.
Giardia Water Filters
Tips and recommendations on avoiding giardia and using water filters while backpacking, trekking and hiking.
MSN eShop: Water Filters and Purifiers
A shopping site which also mixes in consumer information, including decision tips, product types available, and features to consider.
Outside Online - 2002 Buyer's Guide: Water Fi
Outside Magazine's guide to water filters and portable hydration systems, including general information plus reviews, descriptions, and photos of the gear tested by their experts.
TheBackPacker.com
Reviews of water filters, as submitted by the users.