It could either be the shutoff valve or the fill valve in the toilet.
Toilet fill valve slow shut off.
With your right hand hold onto the gray.
If your shutoff is a gate valve turn it many times to open and close these sometimes are affected by mineral deposits.
Sometimes there s buildup in the valve so cleaning should help open.
However when the fill valve is not shutting off the water once the tank is full chances are that the toilet fill valve is faulty.
Place your left hand on the top of the valve cap and while placing your left hand thumb on the side of the arm.
If that doesn t help you might need to clean the pump and valve.
4 24k subscribers turn off water supply and flush the tank.
Replacing this with a quarter turn ball valve is pretty straight forward and will ensure reliable service for the indefinite future.
Reach inside the tank with your right hand under the float cup and lift it up.
Flush out the toilet fill valve on a slow filling or noisy toilet.
The fill valve is usually designed to shit off the water flow when the tank is already full.
Steps for removing the top cap and flushing out debris from the fill valve.
Place your left hand on the top of the valve cap and while.
Turn off water supply and flush the tank.
Reach inside the tank with your right hand under the float cup and lift it up.
Depending on your water pressure a tank usually refills in about three minutes.
Make sure the water shutoff is completely open for maximum water flow.
A slow filling toilet tank is a relatively common problem.