It is important you keep your budgies cage very clean for it to be free from parasites and stay healthy. Once a day you should wash out seed dishes with hot water and dry them thoroughly before refilling them. Remove empty husks, uneaten food and droppings from the floor of the cage and wipe across the perches and cage bars with a damp cloth.
Once a week you should completely empty the floor tray and wash it hot water remembering to completely dry it afterwards. Put down fresh sand or sandpaper and gravel. Scrub the perches clean, if they have become smooth you should rub them with sandpaper to roughen them so your budgie can get a good grip on them. Finally wash all the toys, ladders and any extras you have in the cage.
Once a month you must scrub the entire cage with hot water and rinse and dry off well. Do not use soaps or detergents, as they are harmful to birds, even just the fumes of these products are hazardous to your bird's health. You can also spray a mite spray to keep the cage pesticide free that you can purchase from your local pet shop.
The best time to clean the cage is to take advantage of the times when you let your budgie out to fly. Always remember to dry everything you clean off thoroughly before you let your budgie back into the cage.
Your budgerigar will keep its feathers clean by preening themselves, they can achieve this better if their feathers are slightly damp. Every other day you can give your budgie a saucer of lukewarm water to bath in, fill it no deeper than 2.5cm so they can happily splash in it.
Another useful method is to spray your budgie with water using a plant sprayer, set it to spray, not jet fire, and pump the water onto the bird, sometimes they will spread their wings wide to get them covered in water. You should only offer water this way before the middle of the day so they have plenty of time to dry before evening, avoid giving these water baths at cold winter times and ensure there are no draughts around when your budgie is wet.