Bird do not get a bath in the wild they only get a shower when it rains. Spray your birds with a warm water mist and they should start preening (cleaning themselves).
You can spray your birds 2 x a day with a spray bottle ,and you can soak`em,in the summer you can soak`em 4 x or more if you see that they are panting with there mouth open....good luck
They should bathe daily or everyother day or once a week, if they are healthy and not over stressed.
I have a got a pair of cockatiels n a pair of pides. How often should i give them a bath in summers. N what temperature should b of the water