Thirsty? Water is more common than you think

Water is abundant throughout the entire universe. What water has going for it is that its constituents, hydrogen and oxygen, are also ridiculously common, and those two elements really enjoy bonding with each other. Oxygen has two open slots in its outmost electron orbital shell, making it very eager to find new friends, and each hydrogen comes with one spare electron, so the triple-bonding is a cinch.