Deuteronomy 23:10-13

10If there is someone among you who is impure because of some nocturnal emission, he must leave the camp; he may not reenter it immediately.

11When evening arrives he must wash himself with water and then at sunset he may reenter the camp.

12You are to have a place outside the camp to serve as a latrine.

13You must have a spade among your other equipment and when you relieve yourself outside you must dig a hole with the spade and then turn and cover your excrement.