Trees can indeed offer a source of water. Their internal structure involves the continuous movement and storage of water, making it possible to access the water contained within them.
How Trees Hold Water
Trees have an internal system for water transport and storage. The xylem, a network of specialized cells, moves water and dissolved minerals from the roots to the leaves. This fluid is called xylem sap.
Sap is primarily water, containing dissolved nutrients and sugars. Sap flow is driven by transpiration, where water evaporating from leaves pulls more water up from the roots. Freeze-thaw cycles can also create pressure within the tree, contributing to sap movement.
Techniques for Extracting Water
Water can be extracted from trees using several methods, depending on the species and conditions. Tapping trees like maple and birch for their sap is a well-known technique. This process typically involves drilling a small, angled hole, 1.5 to 2 inches deep, into the tree trunk. A spile (spout) is then inserted to allow sap to drip into a collection bucket. Tapping is ideal in late winter or early spring when fluctuating temperatures create sap flow.
Another method involves cutting certain types of vines, such as wild grapevines. To collect water from a vine, make a cut completely through the vine at a low point, then make a second cut about a foot or more higher up the vine. This second cut allows air to enter, breaking the vacuum and enabling water to flow from the lower cut. The collected liquid should be clear, and it is important to act quickly, as the flow from a vine will typically stop within 20-30 minutes after cutting. Some bamboo species also store water in their hollow culms, accessible by piercing the stem.
Ensuring Water Safety
Water collected from trees requires safety consideration. While sap is mostly water and consumable, it is not sterile and may contain bacteria or environmental contaminants. Purification methods are recommended for any collected tree water, especially if it is to be consumed in a survival context.
Boiling water for at least one minute is a reliable method to kill most pathogens. Filtration can remove larger impurities, and chemical treatments can also be used. Identify the tree or vine species accurately before collecting water, as some plants, like wisteria, produce toxic sap. Discard discolored or cloudy sap.
Realities of Tree Water Collection
While trees provide water, the quantity and effort involved require realistic expectations. The amount of water from a tree is generally small compared to daily hydration needs. For example, it can take 40 to 50 gallons of maple sap to produce just one gallon of maple syrup, illustrating the low sugar concentration and high water content. A healthy tapped birch tree might yield about a gallon of sap per day.
Collecting tree water often requires significant effort for minimal yield, making it a supplementary rather than primary source. The process is seasonal; maple and birch sap flow depends on specific temperature fluctuations in late winter and early spring. If done correctly and in moderation, tapping generally causes minimal harm to the tree, with tap holes healing over time. However, trees are not a consistently reliable long-term water source due to these limitations.