Bamboo is a fast growing grass found across the world, and is common in many jungles and rain forests. Trekking through the jungle is tiring work, often requiring cutting a path and negotiating fallen trees, especially where the jungle has been deforested and then regrown with far more underbrush at ground level. It is easy to get lost, tired and dehydration happens quickly due to the heat and humidity. If you find yourself out of fresh water and not near a stream, you can get a drink from a friendly bamboo plant.
Bamboo grows in discrete cylindrical sections which are hollow and walled at the top and bottom. These sections contain fresh, drinkable water.
First locate a likely clump of bamboo. It must be one of the large species that grow to the height of small trees, with thick stalks typically a dozen cm (five inches) in diameter. You will also need a parang, machete or similar chopping tool. Lastly you will need to find a small bamboo shoot about one cm (half an inch) in diameter.
Cut the small piece of bamboo to around 20cm (eight inches) long. Bamboo often has microscopic hairs on the outside which can irritate the skin, so clean the outside with a leaf or your shirt to get them off. Check that it is hollow and clear all the way down. This will be your drinking straw.
Now open up a section of the big bamboo trunk. Make a cut about half way down the section, and then one a little above it. When you chop, make sure it is a diagonally downward movement. It's all in the wrist. Without removing your blade from the second cut, twist the knife to pry away the section of the wood between the two cuts. Look into the hole you have just made and you should be able to see some water at the bottom of the section. If there is none, try another section. Smell the water. If it smells bad leave it. Next put your homemade straw into the hole and suck up a little water. If it tastes bad leave it, if it tastes nice then drink up!
You won't get much water from a section, but a few should yield enough to last you until you find a stream or civilization. Taking water from a bamboo plant should not harm it as long as it remains standing. Bamboo is particularly fast growing and you would struggle to kill off a clump of it armed only with a knife if you tried.