When you enter a precinct of a Shinto Shrine or a Buddhist temple in Japan, you will usually find a purification fountain called “temizuya”.
■ Purification fountain
The Purification fountain is usually an open area where clear water fills one or various stone basins. Wooden dippers or ladles are usually available to visitors.
Water is being poured from the mouth of a dragon statue. This water is said to be holly water, because a dragon is believed to be a god of water in Japan.
■ How to purify
Worshippers and casual visitors are asked to purify themselves before entering the sacred place of a shrine or a temple. The act of purification is done as follows.
①At the purification fountain, take one of the dippers, fill it with fresh water.
②Holding the dipper in your right hand, pour a bit of water on your left hand.
③Transfer the dipper to your left hand, then pour a bit of water on your right hand.
④Transfer the dipper back to your right hand and pour water into your cupped left hand.
⑤Then rinse your mouth out and spit out the water into the area provided.
⑥Pour water one more time over your left hand.
⑦Tilt the dipper up and let the remaining water pour over the dipper's handle to clean for the next person.
You are not supposed to transfer the water directly from the dipper into your mouth or swallow the water for a sanitary reason.
Ref. A complete guide to Japanese culture and scenic spots in English (written by Ueda, published by Goken)