Processing water to ensure it is safe to drink is typically done by local authorities long before we turn on our taps at home. Even then, many people choose to use an additional water filter to attain the purest quality. So, what happens when there is no clean tap water nearby, for example, in a wilderness survival situation? An easy and effective solution is to build yourself a makeshift water filter using wood.

You don’t need much: a piece of sapwood, a plastic tube, and a clamp or fastening.

Building Your Filter

Source Your Materials

Sapwood is the first and most important part of the water filter. It is the light-coloured, living layer of any tree, branch, or woody stem that exists between the outer bark and the inner heartwood. It is here that the water passes through from the roots to feed the leaves.

You will also need a portion of plastic tubing, ideally a minimum of 15 cm (6 inches). Choose longer tubing to increase the water pressure and filter more water in a shorter period of time.

The final requirement is some sort of clamp or fastening device. A hose clamp works well.

DIY Wooden Water Filter in 3 Steps

Step 1: Begin by sourcing your wood. Cut off a small piece of a tree branch, for example, pinewood, around 7-10 cm (3-4 inches) long and narrow enough that it will fit inside the plastic tube. Strip off the bark, so you have only the pale inner sapwood left.

Step 2: Insert the piece of sapwood into one end of your plastic tube, and use the hose clamp to secure it tightly, making sure that there can be no leaking water escaping from around the wood. If you have any glue handy, you can use this for an extra water seal.

Step 3: You are ready to use your filter. Holding the tube with the wood piece at the bottom end, pour water into the top of the tube. Remember to place a clean bucket, bottle, or container below to catch the water when it drips through your sapwood filter.

The Xylem Filter

It was a research team at the Massachusetts Institute of Technology (MIT) that discovered the efficacy of sapwood as a water filtration system almost 10 years ago. The natural structure of the wood, made up of a porous tissue called xylem, is designed to filter contaminants as small as 70 nanometers from tree sap as it passes through the tree roots to the crowns.

The xylem filter was found to be up to 99% effective in removing bacteria such as E.coli and can produce up to four litres of fresh, clean drinking water in a 24 hour period.

Final Thoughts

Now that we know the steps of how to make a homemade water filter out of wood, let’s watch this video to see whether wood can actually produce pure water:


Constructing your DIY xylem filter requires minimum effort but offers an extremely valuable aid. This low-tech apparatus could be your saving grace if you were to run out of clean water in the outdoors, for example, whilst on a hiking trip, wilderness camping, or in a similar situation. Sapwood is nature’s answer to water filtration, and now you know how to take advantage of it.

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