I can't emphasise enough on how important is to bring
water along. Always carry water, even in the winter. We went to Death
Valley three times, in January, June and October. We always had water
along and we needed it. In October we went on a 2 miles hike without
water and we came back before we got to the end because we were very
thirsty. Always carry water with you as you hike. Water sources within
the valley are not reliable and often not safe to drink. Plan on carrying
a minimum of 1 gallon (4 liters) of water per person per day. And of
course, be sure to drink the water you bring ;-)