The best way to clean the syrup lines of a soda fountain is to flush the tube system with an over-the-counter cleaning solution devoid of bleach. Bleach corrodes the plastic in the tubes and may cause health problems. These cleaning solutions are designed as bags-in-a-box, which are similar to the syrup supply boxes used in soda fountains.
Syrup supply bags are hooked up to the dispensary tubes using a BIB adapter. This same adapter is used to connect boxed cleaning solutions to the soda fountain tube system. This cleaning process works in exactly the same way as when the soda machine is dispensing syrup. The cleaning solution is hooked up to the soda fountain where the syrup supply bags are normally stored. Then the lever on the front of the soda dispenser should be depressed, allowing the cleaning solution to flush the system. The cleaning solution should be run through the tube system for 15 to 20 minutes.
Time Magazine ran a story highlighting the need for soda fountain syrup tube systems to be cleaned and flushed regularly. The article states that after conducting a study of 30 different soda fountain systems in Virginia, 48 percent were found to contain coliform bacteria, normally associated with human and animal feces.