The other day, it not only backed up, but overflowed dumping about an inch of water on the bathroom floor before I noticed it and shut off the water. It has never done that before.
As I understand toilet hardware, the overflowing is caused by a double failure: the shutoff valve in the tank failed to turn off the water and the blockage in the line prevented the extra water from draining away.
I cleared the blockage and turned the water back on. It has been running normally for about a week. I stay there until the water shuts off.
My question is should I replace the hardware in the tank? I believe it was replaced just a couple of years ago. I am afraid that it is going to fail again and I might not catch it before there is real water damage.
To my knowledge, the shut off mechanism has never failed before and it has not been working for a week. Is it normal for it to fail just once without it being defective and likely to fail again?