How to Vent a Bathroom Toilet

Find a good place to install the vent valve on your toilet drain pipe. Follow the drain pipe from the toilet beneath the floor where the toilet is installed to the home's main drain line.

Pick a spot where you have access to the line and can install the valve. Make sure the there is enough clearance overhead for the valve. If not, choose another spot on the drain line.

Cut through the drain line with a pipe saw at the point where you choose to install the air vent valve. If this is a new installation, hold off on connecting the last section of drain pipe to the drain stack.

Insert a T-fitting between the two sections of pipe you created when you made the cut. Alternatively, insert it between the last section of drain pipe and the drain stack if this is a new installation.

Install the air admittance valve onto the end of the fitting without cement. Check the clearance again and adjust as necessary.

Remove the fitting and valve. Coat both ends of each with PVC cement. Reinstall the fitting and valve, positioning them so the valve is facing up in a vertical position. Allow the PVC cement time to dry before flushing the toilet. This takes at least four hours or as indicated on the packaging instructions.