[99] Now at that time bhikkhus bathed here and there in the monastery grounds. The grounds became muddy. They informed the Blessed One of this matter. He said: "Bhikkhus, I allow a soakage pool for the water (udakacandanikā)." The pool was exposed. Bhikkhus were ashamed to bathe. … He said: "Bhikkhus, I allow it to be enclosed with three kinds of walls: a brick wall, a stone wall, and a wooden wall." The pool became muddy. … He said: "Bhikkhus, I allow three kinds of paving to be laid down: brick paving, stone paving, and wooden paving." The water stood stagnant. … He said: "Bhikkhus, I allow a water drain (udakaniddhamana)."
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.