I sell the stuff (CamelBak), have tried the baking soda and water thing (never heard of Listerine, but sounds like it would do ok) and it works ok too, but nothing works like the cleaning kit (comes with the brushes, dryer hanger, and a couple of cleaning tablets). I held off for 7/10 years using baking soda, but nothing works like the tablets. It makes a new one taste better too along with keeping up on your existing bladders. Lastly, if you want to keep your bladder, hose, and mouthpiece fresh keep it in your refer if you have the room. If it stays cold, you almost never have to clean it out except for maybe the mouthpiece. I also recommend using the Elixer (their brand of electrolyte replenishment) as it adds kind of a citrus-like flavor that keeps it tasting less like plastic. Good luck