When trying to replace a toilet, the water valve to toilet will not stop water supply even when valve is shut off. I have opened and closed the valve several times but water continues to be supplied to toilet.
It is very common for the "stop valve" (the local water supply shut-off valve for a plumbing fixture) to leak by. Over the years the rubber bibb washer either softens to the point that is disintegrates when tightened down against the valve seat, or calcium scale or/and mineral deposits prevent proper sealing. Try opening and closing it a few more times, then use pliers to actually force it closed. Any of the following scenarios could play out:
- the water flow will stop*
- the flow will not stop*
- the handle will break or be crushed and the flow will not stop*
*these scenarios require you to shut off the main water supply to the house/area and repair or replace (most likely replace) the stop valve.