Tsukubai, a tiny purifying basin, is located at the entrance of the tea house and ritually purify themselves by pouring some water over their hands here. Tsukubai in Kyoto Ryoanji Temple is famous, Four Chinese characters, 吾唯足知(“ware tada taru wo shiru” (I simply know what is enough)) “are carved there. The feature of the stone is the square water hole in the centre of the stone, where the water is stored, forms a part of each letter.

つくばい（蹲踞、蹲）とは、茶室に入る前に、手を清めるために置かれた背の低い手水鉢に投石をおいて趣を加えたもで、手水で手を洗うとき「つくばう（しゃがむ）」ことからその名がきました。「そんきよ」とも読み、相撲や剣道で屈んで座る姿勢のことを指します。