In most cases, the main source of wai for the lo‘i is either a waterfall or spring that feeds the stream or river with flowing water. Because of this, lo‘i were built near to the streams so that water could be easily obtained. Irrigated ditches, or ‘auwai, carried the water from the stream or river to the lo‘i. Traditionally, a mānowai, or dam, was built to divert a portion of the water flowing in the stream into the ‘auwai. The mānowai may also be known as the po‘owai, as this is the source, or the “head,” for the water that flows in and out of the lo‘i. The ‘auwai also carried the water back to the stream or river. This ensured that the water would continuously flow in and out of the lo‘i and not become stagnant. Stagnant water causes the kalo to rot and become unusable.

Uncle Calvin Hoe discusses the importance of wai (water) to Hawaiians culturally and its necessity for kalo farming.  In addition, he mentions some pilikia (problems) that exist when it comes to water.