Purified drinking water is available at only a few locations in the canyon. Always carry water with you. Water may be obtained directly from the Colorado River and Bright Angel Creek, but must be treated before drinking. Most other water sources in the canyon are intermittent and unreliable. Because of occasional pipeline failures, it's a good idea to be prepared with one of these methods even when hiking Corridor trails.
Eating is equally important to both day hikers and overnight backpackers.
Carry high energy snacks as well as meals. The hike out is much easier when you provide your body with enough calories to support the extreme physical activity you're engaged in. There are many small animals who will damage your pack and eat your supplies if not secured properly. Improper food storage and feeding harms wildlife. Violators will be cited.