The bamboo trunk is compose of several "water chamber". Making a hole on the bottom of one of those chamber make the water flow pretty well, making it easy to filled up a bottle. Just one think to be carefull, is to the presence of little black spot around the chamber. If there is that mean an insect layed egg inside tainting the water, making it grayish, smell and taste bad and can make you sick. If there no black holes, then the water perfectly good to drink.