How to Find Subsurface Water
Emergency water sources come form surprising places sometimes. Whether from the ground or from plants, a little work and creativity can yield sufficient water to keep you alive for a long time should the need arise. Here are some alternative tactics to try when the more common water sources aren't available.
Create a Beach Well
If you have no supply of fresh water available, but you are beside an ocean, building a beach well is worth your time. First, select a location away from the shoreline and beyond the first sand dune. Ideally, this location will be surrounded by lush, green vegetation. Start digging a hole and only stop when water begins to seep in to it. Once it does, reinforce the walls of the hole with rocks and twigs so that they don't collapse. Allow the water to sit overnight so that the dirt and sand settle to the bottom.
Dry Riverbeds Could Still Provide Water
A dry riverbed indicates that water once passed through the area. It doesn't necessarily mean that there is no longer any water below the surface. To find out, select a location in the that has the greatest potential for yielding water such as at a bend or where lush vegetation is present. Dig a hole up to three feet deep. If at that depth there is no water, move on to another site. If water does seep in, reinforce the walls of the hole with rocks and wood. And like the beach well above, let the water sit overnight to allow the sediment to settle.
Water from Plants
If you're in a survival situation in a desert, look for Barrel cacti as they can provide a limited supply of water. Once located, cut off the top of the cactus using a large knife, remove the inner pulp, and place it inside a porous material, such as a cotton t-shirt. Wring the t-shirt to extract the water from the pulp in to your mouth or an awaiting container. Don't eat the pulp as it will require more energy and body fluids to digest than you will obtain from it.
In tropical forests, banana trees are common enough that you might find one. These trees can provide an almost unending supply of water. To get water from a banana tree, you need to cut one in half with a knife or machete about 3 inches from the ground and then carve a bowl into the top surface of the trunk. Water will almost immediately fill the bowl, but you want to discard this first batch along with 2 or 3 others. Drinking any of the first batches will upset your stomach as well as taste bad.
Also in tropical forests are water vines. Once you locate one, make a cut high up on the vine and then make another cut lower on the vine. Then just let the water drain into your mouth or container. Although water from most of these vines is safe to drink, avoid those that have a bitter taste or color sap.
Note: Don't disturb native vegetation in wilderness areas unless an emergency survival situation exists.
Wilderness Survival by Gregory J. Davenport