I am remodeling a bathroom in a 150 year old house so there are several unusual features. I want to move a toilet that is on a 3 inch copper line 6 feet away from the 3 inch copper drain stack. It is currently 2 feet away. The vent at the main stack is 2 inches and it is at a 90 degree angle to the stack. It runs about 5 feet before it turns 90 degrees goes up into the attic and snakes around and then exits through the roof. During this 5 feet of nearly horizontal (slopes ¼ inch per foot) run the vent also catches a 1 ½ inch tub drain. Everything works as it is however I was concerned that moving the toilet 6 feet from the stack might cause a problem. Will it? I also want to add a sink to this horizontal wet stack that would also be six feet away. Can I do it without adding a vent closer to the sink which structurally would be very difficult? Would using a 2 inch waste for the sink be a good idea?

I am remodeling a bathroom in a 150 year old house so there are several unusual features. I want to move a toilet that is on a 3 inch copper line 6 feet away from the 3 inch copper drain stack. It is currently 2 feet away. The vent at the main stack is 2 inches and it is at a 90 degree angle to the stack. It runs about 5 feet before it turns 90 degrees goes up into the attic and snakes around and then exits through the roof. During this 5 feet of nearly horizontal (slopes ¼ inch per foot) run the vent also catches a 1 ½ inch tub drain. Everything works as it is however I was concerned that moving the toilet 6 feet from the stack might cause a problem. Will it? I also want to add a sink to this horizontal wet stack that would also be six feet away. Can I do it without adding a vent closer to the sink which structurally would be very difficult? Would using a 2 inch waste for the sink be a good idea?

Moving the toilet 6' will present no problem although I'm interested if you plan on converting from copper drainage and what you wish to convert to.
However you failed to give me enough details about the vent you plan on adding a lavatory to. What does this originally vent? How high off the floor line is the horizontal vent pipe? If the horizontal vent pipe is real low then you will have to vent the sink. However you may use a mechanical spring loaded vent and not have to run any pipe. Code calls for 5' between trap and vent with a 2" drain. But If there's no permits pulled and you won't be inspected you can "fudge" a little on the distance. Good luck, Tom

Tom thanks for the reply. My plan is to cut the copper put in a fernco fitting and then run PVC. I am a novice and open to other ideas. The horizontal wet vent is at floor level and accepts (in order of furthest distance from the main stack) a 1 ½ inch tub drain, the proposed 2 inch sink drain, and the toilet. As I mentioned the main stack makes a 90 degree turn directly above the toilet connection. I used a 3 inch 90 degree elbow with a 2 inch side inlet for a shower and then sized down the horizontal wet vent to 2 inches before the tub and sink connections. Does everything sound OK? Let me know if you need further clarification. Thanks again.

Tom thanks for the reply. My plan is to cut the copper put in a fernco fitting and then run PVC. I am a novice and open to other ideas. The horizontal wet vent is at floor level and accepts (in order of furthest distance from the main stack) a 1 ½ inch tub drain, the proposed 2 inch sink drain, and the toilet. As I mentioned the main stack makes a 90 degree turn directly above the toilet connection. I used a 3 inch 90 degree elbow with a 2 inch side inlet for a shower and then sized down the horizontal wet vent to 2 inches before the tub and sink connections. Does everything sound OK? Let me know if you need further clarification. Thanks again.


In order to connect to a drain on the floor with your lavatory you would have to install a "S" trap. This is illegal and outlawed by ALL local, state and Universal Plumbing Codes. You Must run a vent on the lavatory. How far will the lavatory be from the vertical dry vent? If you can tie to that you won't need a vent. The distances between trap and vent go like this.

1 1/2" *** 3 1/2" ft.
2" ****** 5 ft.
3" ***** 6 ft.
4" ***** 10 ft.

If you can't tie back to the dry vent consider a mechanical vent mentioned earlier. Regards, Tom