Giving a quaker parrot (Monk Parakeet) a bath, can be a difficult thing to do, but it is neccessary for good health and hygeine.

There are actually several methods available, depending on the circumstances like whether you have a breeder / finger eater or if you have a tame / touchable bird:

• The Sink Shower. Let your bird perch on your hand while slowly moving it close to a slow running faucet. If it is interested, it will dunk itself under the water. Do NOT force it. This method may be unsuccessful the first few times, just keep trying for a few days.
• Wet Hands Bath. Try to get your bird to step up while your hands are soaked with clean water. If successful, try petting it with your free hand (Which is also water soaked). This will help get it used to water being on its feathers and skin.
• Mist Spray bottle. Take the bottle and mist spray far above the bird, do not spray directly at them, as they generally hate it when that happens. If it is absolutely neccessary to mist while it is in the cage, wipe down the bars and bottom afterwards because mold can form within hours of spraying.