Ôharai : purification rite

There is no way you went visiting a temple or a shrine in Japan without seing those little house with a bassin.

Those are called chōzuya or temizuya (手水舎)
Before entering the Shaden (社殿 : main building) of a Shinto sanctuary your are supposed to purify yourself from all sins and faults.

For this, you fill up the Hihaku (柄杓 :  laddle) with water.
Your first pour water on your left hand, then the right hand before putting water on your mouth and finally, slowly raising the Hikashu vertically to wash it and left it pure for next user.
This purification rite is called Ôharai (お祓い). It is actually a short simplified version of a proper purification rite which was usually performed in a river or in the sea.

The Chôzuya or Temizuya are very often shapped as dragon.
The can also be simply carved in stones ....
... and then sometimes you get to discover an unusual shape :

The beautiful Lotus Bassin of Araiyakushi Baishoin

The rare cow shapped from a little temple near Kyoto imperial castel

Dragons Chôzuya of Tokyo