Pakiṇṇaka 17

The Buddha was staying in Sāvatthī. At that time, the World-honored One had laid down the precept that it’s not allowed to wash a menstrual cloth at the men’s bathing place. Then bhikkhunīs went to the place where guests wash their clothes to wash it. … “It’s not allowed to wash a menstrual cloth at the place where guests wash their clothes. One should put it into a tub or another clay utensil, and wash it in a secluded place. When washing it, she may not take the water, and pour it on the ground. She should take the water to a ditch, or a place where nobody can see it. The cloth should be put out in the sun to dry. Later when she needs it, she should use it. If a bhikkhunī washes a menstrual cloth at the place where guests wash their clothes, she breaks a minor vinaya rule.” This is called the rule on the guests’ clothes-washing place.