What is the way to let the gray swallows take a bath

If you want to let the gray swallow bird take a bath, you can provide it with a water box. It will wash it by itself. The birds are more clean.If you don't wash it, you can spray it with a watering pot.The length of this bird is about 18 cm. The upper body is pale gray. It usually eats insects, crustaceans and software animals. It is mainly distributed in Yunnan and Tibet.