Galvanized tanks can withstand a good disinfection every once in a while, but after it is disinfected, you must empty it kinda quickly. Large amounts of chlorine, if left in the tank too long, will eat away at the tin used to galvanize the metal. For the correct levels of chlorine to use to disinfect the tank, go to www.endtimesreport.com is a very good article there to tell you the amount to use.