Baby Parrots May Not Drink Water...
Baby parrots (chicks) that were originally fed formula by their previous owner may not drink regular water as of yet. If you recently adopted a baby parrot, check with the former owner to see what they feeding it. Typically, baby parrots are given a special formula that's mixed with water; thus, providing the chick with both food and water.
Unless otherwise specified by your avian veterinarian, continue this water-soaked formula diet with your chick until they are ready for solid foods, at which point you can introduce water into its cage.
Offer Two Sources of Water
There's no denying the fact that parrots are finicky creatures that prefer to do things "their own way." As a result, some parrots will only drink water from dishes, whereas others will only drink from a bottle. If your parrot is hesitant to drink water in cage, try adding both a dish and a bottle. Having two sources of water will increase the chance of them drinking. While this doesn't always work, it's certainly not going to hurt either.
Introduce Your Parrot To Water
Is your parrot familiar with the source of water in its cage? If not, you should encourage them to explore it by tapping your fingers in it. Avoid splashing water on your parrot, as this may scare them away, but instead draw attention to the dish/bottle by playing with it. You can even place a treat inside the water. Hopefully, this will trigger your parrot's curiosity, causing them to check out the water.
If you've exhausted all of the options listed above and your parrot still isn't drinking water, call and schedule an appointment with your veterinarian. Most parrots will drink before going into severe dehydration, but certain diseases and underlying conditions may restrict their ability to drink. Only a professional avian veterinarian will be able to identify such conditions and offer guidance on how to treat your parrot.