I used to use water bottles, but like you, I changed to something larger.....
I ended up getting one of those ultrasonic jewelry cleaners (they're really just vibrators) to clean the water bottle tips because of the food buildup my birds would force into the tube licking it.....I started out using a pipette/test tube brush to try cleaning the stainless tube out, that worked for the tube but wouldn't clean the stainless ball, so tried the jewelry cleaner & was satisfied with it except it took a bit longer to run them through the cleaner tray than I liked.....
In the end, I decided stainless bowls and/or crock bowls were easier to clean.....
