I know of no flapper that will not need replacing sooner or later. Chlorine is your enemy, but it is necessary to keep water safe to drink and we use the same water source for drinking as for flushing. One thing not mentioned is not to use chlorine tablets in the tank. That added to the chlorine already in the water supply is a real killer. I have had little problem with flappers, but I keep a space nearby for the time when one fails. Side cutters work well to get stiff tabs off. Also, when replacing flappers, clean the hole where the flapper seats with Scotch Bright or SOS.