Fix-It Chick: Remove a whole house trap

Whole house traps were installed in most homes built before the 1940s. Originally installed to keep dangerous sewer gases (and rats) from entering the home, these u-shaped cast-iron antiquities are now virtually obsolete.

If a home has separate traps for each plumbing fixture or appliance, it is often a good idea to remove the whole house trap before it collapses and causes sewage to seep into places it does not belong.

Step 1: Most whole house traps have two 3-inch to 4-inch threaded access plugs — one to access the sewer line running to the street and the other to access the main drain line that runs through the home. It is not unusual to find the street side plug located beneath the home’s foundation wall.

Step 2: The hardest part of removing a whole house trap is accessing it. Use an electric demolition hammer or a sledgehammer to break away the concrete surrounding the access plugs. Remove the rubble piece by piece to expose the whole house trap.

Step 3: Dig down beneath the whole house trap and remove the dirt and rubble until both the sewer line and the main drain line sides of the trap are exposed and there is adequate access to trap.

Step 4: Use a chain-style soil pipe cutter to snap off the cast-iron pipe on either side of the trap and remove the trap.

Step 5: Purchase two rubber couplings, a section of PVC pipe and a clean-out fitting the same diameter as the cast-iron drain line.

Step 6: Cut two short pieces of PVC pipe to go into either side of the clean-out fitting. The total length of the pipe and fitting should equal the gap between the two open ends of the drain line.

Step 7: Clean, prime and glue the two sections of pipe into the clean-out fitting.

Step 8: Loosen the clamps on the rubber couplings and slide a coupling over each of the two exposed drain pipe ends.

Step 9: With the cast-iron pipe protruding slightly from the rubber coupling, position the PVC pipe and clean-out fitting into place.

Step 10: Slide the rubber couplings up onto the PVC pipe until half the fitting covers the cast-iron and the other half covers the PVC.

Step 11: Tighten the clamps and test for leaks by flushing the toilet several times.

— Have a home improvement question for the Fix-It Chick? Email it to Linda Cottin at