How Do Trees Drink – Where Do Trees Get Water From

Large Rooting Tree Near A Body Of Water
(Image credit: Richard McMillin)

How do trees drink? We all know that trees don’t raise a glass and say, “bottoms up.” Yet “bottoms up” has a lot to do with water in trees. 

Trees take up water through their roots, which are, quite literally, at the bottom of the trunk. From there the water travels up and up. To hear more about how trees absorb water, read on. 

Where Do Trees Get Water?

Trees need sunlight, air and water to thrive, and from the combination, they are able to create their own food. That happens through the process of photosynthesis that takes place in the tree leaves. It’s easy to see how air and sunshine gets to the tree’s canopy, but where do trees get water? 

Trees absorb water through their roots. Most of the water a tree uses enters through the underground roots. A tree’s root system is extensive; the roots extend out from the trunk area much further than the branches do, often to a distance as wide as the tree is tall. 

Tree roots are covered in tiny hairs with beneficial fungi growing on them that draw water into the roots by osmosis. The majority of the roots that absorb water are in the top few feet of soil.

How Do Trees Drink?

Once the water is sucked into the roots via the root hairs, it gets into a sort of botanical pipeline in the tree’s inner bark that carries the water up the tree. A tree builds additional hollow “pipes” inside the trunk every year to transport water and nutrients. These are the “rings” that we see inside a tree trunk.

The roots use some of the water that they intake for the root system. The rest moves up the trunk to the branches and then to the leaves. That is how water in trees is transported to the canopy. But when trees take up water, the vast majority of it is released back into the air.

What Happens to Water in Trees?

Trees lose water through openings in their leaves called stomata. As they disperse the water, the water pressure in the upper canopy drops that the hydrostatic pressure difference causes the water from the roots to rise to the leaves. 

The vast majority of water a tree absorbs is released into the air from leaf stomata -- some 90 percent. This can amount to hundreds of gallons of water in a fully grown tree in hot, dry weather. The remaining 10 percent of the water is what the tree uses to keep growing.

Teo Spengler

Teo Spengler has been gardening for 30 years. She is a docent at the San Francisco Botanical Garden. Her passion is trees, 250 of which she has planted on her land in France.