also: ちょうずや
noun
purification fountain; ablution pavilion
A roofed water basin at Shinto shrines where visitors rinse their hands and mouth before praying. The reading てみずや is more common, but ちょうずや is also widely used.
神社に入る前に、手水舎で手と口を清めましょう。
Before entering the shrine, let's purify our hands and mouth at the purification fountain.
あの神社の手水舎はとても立派ですね。
That shrine's ablution pavilion is really impressive, isn't it?
Compound of 手水 (hand-water, purification water) and 舎 (building, pavilion). The reading てみず is a kun'yomi combination, while ちょうず is a sound shift from てみず.