I have a five and a three-gallon jar. Assuming there is an infinite supply of water, how can I measure one-gallon water?

Easy Gallon Riddle

-> Fill up the 3 gallon jar first , Pour it into the five gallon jar.
-> Fill up the 3 gallon jar again, and fill up the rest of the 5 gallon jar,
=> and you should have 1 gallon left over in the 3 gallon jar.