Incomming water to toilet

[GOFNUTS]

The black washer behind the toilet blew off while flushing the toilet and water went everywhere. I attempted to put the washer back on but each time water flys. I have a preasure adpter on the water line but the washer still flys off. I have looked for other pieces that may have blown off but found nothing. Has anybody had this problem, if so, what did you do to fix it. Your help is appreciated.

[Larry]

Are you talking about the rubber grommet that holds the vacuum breaker in? If so, it sounds like it has harden up...time for a new one.