there are two popular ways to make your own fresh water. the first and easier way is to dig a large wide but shallow hole and cover it with plastic. use rocks around the edges to keep the plastic in place. under the plastic, place a container for your water and let it sit over night. the dew and moisture will collect and stick to the plastic and slowly drip into your container. placing a very small stone in the center to make the plastic concave will help the moisture to drip towards the center. filling the hole with freshly picked leaves and grass ( all green of course) will make this work in the daytime when there is no dew. this is called sweating water from plants. the other way to get fresh water is the same sweating process but you take a sandwich bag or other small plastic as your collection container. bunch up as many leaves from a tree together and place the bag around them, holding it all together with a rubber band or trash bag tie. (or anything else for that matter). this takes alot of baggies for a good amount but these two methods together can get you fresh water until you find a good source. remember to make more than one hole for as much water as you can get.

Good article