Your next priority is water. You can survive a long time without food, but only days or even less without water. Water is vital to your survival. There is no substitute for water. Never drink blood or urine. They will only hasten dehydration. Alcohol not only isn't a substitute for water, it can lower body temperatures and cause other problems for survivors. Smoking will also hasten dehydration and should be avoided unless water is plentiful.
With no tap to turn on, you will have to find water where you can. Dew can be collected off surfaces and plants. With snow on the ground, water is readily at hand. However, never eat snow or ice as it will lower your body temperature. Melt it by either placing it in a container between clothing layers or over or next to a fire. You can even gather snow in cloth material and hang it well above the fire with a container suspended underneath to catch the water as it slowly melts.
When melting snow directly over a fire, be sure to start first with a small amount of water or it will scorch and that tastes truly awful. You really can "burn" water. Ice is less work to melt than snow, having much more water per volume. If you've ended up in a forested or mountainous area, there's a good possibility that water is close at hand. But, be very careful when looking so that you don't become lost or injured. Be careful where you step. Whenever you leave your base camp, mark the trail in some permanent, unmistakable manner. Don't rely on landmarks or you'll get your self even more lost.
In arid areas, lush vegetation is a sign of possible water (and a source of shade). Dig down in dry washes at the base of cliffs, on the outside of a bend and near green vegetation. If you don't hit wet sand within a couple feet, try elsewhere.
Desert solar stills, a customary inclusion in most survival manuals, are marginally effective at best and should be considered a last resort. This involves digging a hole in sandy soil, covering and suspending clear plastic into it and collecting water which condenses on the plastic in a container at the bottom. Water lost digging and preparing one generally cannot be recouped by its output.
Using clear plastic or clear plastic bags as a "transpiration" collector can be a better bet if leafed bushes exist, though even they often only work marginally when you need it the most. Wrapping the clear plastic around green foliage and tying it tight traps the moisture given up naturally by transpiration and increases output because of the trapped solar heat. A rock in the bag or tying it down makes a low point for the water to collect. Barrel and other cactus are also highly overrated as a potential water source.
At many times of the year, the only reliable source of water in the desert is the water you bring along. Sad to say, but even in the most remote wilderness, water from natural sources like streams, creeks and springs must be considered contaminated. Before consumption it should be purified, if at all possible, by boiling, chemical treatment or filtering. Generally, bringing water to a rolling boil is a sure bet to kill the bugs. Contrary to popular myth, it is not necessary to boil water for extended periods or for even longer at higher elevations. Simply bringing it to a boil is all that is necessary to kill those bacteria, cysts and other nasties which can be killed by such temperatures.
Easier and more energy efficient is the use of iodine treatments if done according to directions. Iodine treatments have a poor rating for taste but gets the job done. Water purifier filters are the easiest solution, if you have one that can filter at the appropriate micron level to capture bacteria, cyst and such.. Water treatment is serious business to survival so add a treatment method to your survival kit. Again do your homework before hand.
However, if you have no way, whatsoever, to purify water don't be so afraid of the water that you avoid drinking because you have no way whatsoever to purify it. Do the best that you can and build a makeshift filter if you like. Filtering water through clothing materials, sand, gravel may get the job done. Better, as a last resort, to risk a bout of "giardiasis" (a microbe-induced intestinal disorder), which can take up to a few days to develop (by which time you can hope to be rescued), than to perish from dehydration.
