Extremes I go to, to save weight: Trim the margins off my maps. Remove the tags from my teabags. Cut the handle off my toothbrush. Stop laughing at me! Of course I eliminate all unnecessary packaging—transfer all food items from glass and other heavy or bulky containers to gerry tubes, other plastic containers I carry minimal water—carefully scrutinize topo sectional maps pre-trek, locate all water sources in advance; plan the day’s march from water source to water source, same with campsite. I call it, “Walk to water.” I just don’t get all these “hydration pack things, giant squishy water containers etc”...I think they make too much of it. Water is almost always your heaviest load. I rarely carry more than a quart.
How do you find water in the wild? LISTEN for it. For example, in mountainous terrain, stop dead still, listen for the trickle of a spring, or creek, whatever. Also, the sound of birds. If you begin to notice there’s more birds—visually too—than there was a while ago, chances are there’s water nearby. Birds always know where the water is, if there is any. Of course I realize I’m excluding desert, rockscapes, other very arid terrain…done my share of it. In that case, enough water must be carried, so begin the trade-offs mentioned by others here, to facilitate the absolute necessity of carrying a lot of water, I also of course shorten the lengths, both time and distance, of each segment, day’s journey. Others here are providing a lot of good info too.