How to Keep a Basement Toilet From Backing Up During a Rain

Vent caps sit on top of a vertical vent pipe to protect the pipe from animals and debris.

Drainpipes follow the path of least resistance. A basement toilet uses gravity pumps or other devices to force water upward into the main drain, which typically sits higher than the toilet. The end result is that a strong rainstorm will leak water down the vertical vent pipe into the path of least resistance, which is the basement toilet. Correcting the issue is a simple matter of installing a vent cap on top of the vertical vent pipe.

Things You'll Need

• Measuring tape
• Marker
• Drill
• 1/8-inch drill bit
• Screwdriver drill bit
• Sheet metal screws
• Vent pipe cap

Instructions

1. Measure the outer diameter of the vent pipe located on the roof. Take these dimensions to a hardware store to purchase a vent pipe cap of the proper size.

2. Position the vent pipe cap on the pipe and mark the screw hole locations with a marker. Remove the vent pipe cap.

3. Drill pilot holes into the vent pipe with an 1/8-inch drill bit. The package of sheet metal screws will outline the proper size for pilot holes if it is not 1/8 inch.

4. Place the cap on the vent pipe and align the holes. Drive sheet metal screws through the cap into the pilot holes, using a drill and screwdriver attachment.

Tips & Warnings

• An alternative to a vent pipe cap is a one-way valve installed in the drain line coming off the toilet. The backup that occurs is due to pressure in the drain line from the vent pipe. You can easily install a one-way valve to prevent that pressure from pushing into the toilet drain.

References

• "Lowe's: Complete Home Improvement and Repair"; Don Vandervort; 2005