The white plug is for the elevated dog water bowl. A quick cleaning of a dirty dog dish is simple. Turn the water valve off, pull the plug, clean and refresh the bowl.
The pink plug is used when you install the plastic bowl insert. The plastic bowl inserts are helpful for those pet owners with busy schedules and don't have the time for cleaning the dog water bowl. Every few weeks, to clean, just replace the plastic water bowl insert.
The tiny opaque is the purge plug if you use a Critter Cooler lid with a purge hole in it. They will release the vacuum, making it easier to open the lid. Call or email if you need a lid with the purge hole and watch the new user FAQ video.