A natural spring inside the cave complex was the water source for the entire settlement. The water still runs here, channelled through a stone trough carved into the rock. Locals and pilgrims sometimes drink from it; the water is cold and clean.
The monastery engineers also cut an irrigation channel into the cliff to bring water to the terraced gardens on the slopes below. Parts of the channel are still visible from the path down to the river. The ability to provide water self-sufficiently, along with the hidden entrances, was what made Vardzia defensible as well as habitable.