Travel light. If you're a solo traveler who doesn't like the flavor or lag time of tablets or drops, consider a bottle filter. The dunk-and-drink feature is the quickest way to a cool drink.
Travel even lighter. If you're a solo traveler who likes to move as fast as possible, consider chemical tablets or drops like iodine or chlorine dioxide. These products weigh next to nothing, and one bottle is usually enough for a
Go large when company comes. If you frequently travel with big groups, opt for a big pump and/or gravity-feed filter designed for cleaning high volumes of water.
Remember Plan B. When hiking with large groups or heading out for more than a week, take backup water treatment, whether it's a bottle of drops or a spare filter element. Groups may want to take several filters so poor Joe Bob doesn't have to spend 3 hours pumping 26 quarts of water through the group filter.
Practice before purchasing. Before you buy, ask the salesperson to remove the filter from its packaging and let you pump it. This will give you an idea of each unit's ergonomics.
Figure out your fixes. Take a few minutes to look over the owner's manual. Be sure that the maintenance and troubleshooting sections are clear and detailed, since you'll eventually find yourself sitting by a stream trying to get your filter cranking again.
Dry out early and often. After filtering, pump any excess water out of the unit's system so cooties have less moisture to accelerate growth. Lay it out to dry while in camp. If your chosen filter doesn't come with a mesh storage sack, purchase one separately. The mesh allows better airflow, so your filter dries out more quickly.
Clean the pipes. All filters eventually plug up, so be sure to purchase any extra maintenance equipment for the model you buy. Maintenance kits often include spare O-rings, scrub brushes, and tiny tubes of lubricant.
Prevent freezer burn. When hiking in places where nighttime temperatures dip below freezing, bring your filter into the tent. If water freezes and expands inside the filter, it can crack and ruin the cartridge.
Stop silt cold. Extend the life of your cartridge by using a bandanna to filter particles out of silty or dirty water. When dipping from a particularly muddy stream, let the brown stuff settle to the bottom of a pot before pumping it.