[ifixit]

The knob on the water shut valve for my toilet broke in half. I bought a new knob. Do you have to shut the water main off to replace it? It look like I just unscrew the old one & rescrew in the new knob.

 

[VIPlumber]

Yup, just unscrew & replace. No need to shut the water off.

 

[oh'mike]

I do hope you were just talking about the handle and not the entire shut off valve.

 

[ben's plumbing]

yep thats what i was thinking mike..hope its just the handle and not stem...

 

[oh'mike]

Perhaps op will come back with 'removing wet drywall' question next.

 

[jnc401]

Considering we do not know exactly what the problem is that you are dealing with, it would be best if you turned the water off to the supply to the toilet. If for some reason you were to torque on the shutoff valve, slip and fall against it, or hit it with a tool, it is always safe to shut the water off. This 2 minute adjustment could save you from a very pricey fix if the water were to leak. Always be safe, not sorry.