'S' trap replacement

I have a 100 year old house with an 'S' trap in a 1st floor kitchen sink. The current configuration is the 'S' trap in a 1 1/2" line then a 3' drop to a 2" horizontal cast iron pipe running about 8' to the main stack.

I'd like to know if there are any alternatives to installing a standard wall vent and avoiding a procedure that would require extensive tear out of walls and ceiling on both the 1st and 2nd floors.

Would an air vent like those used on kitchen islands meet national code?

Can it be wet vented in the basement from just where it breaks through the basement ceiling? This would involve a 'T' into the existing drain then running a horizontal line about 7' to 'T' into the vent coming up from the basement laundry sink?

Any other suggestions? Thanks!!

I thought one of the regular licensed plumbers would have answered this with a better answer than this, but let me share what I have learned from this board in some of the past answers. Some of what I give you may not be 100% accurate, and local code may dictate what can or can't be done. As I understand it, an "S" trap is not legal in any code. Air admitance valves, aka Studor or AAV, work, but many plumbers don't like them because of possible failure. They can not be the sole vent in the system, you must be vented to the outside. In other words, it can't be the sole vent. If you are tying into the stack, the connection must be 6" above the highest fixture in the system, so I don't think you can do the wet vent as you described. Sorry to be a bit vague, but you asked a good question and it deserves an answer. Check with the local authorities on the legality of what you are trying to do. They can tell you for sure and possibly offer some other ways to do the job.

s traps and life in general

if you got an s trap, and it has worked fine for 100 years,
a new s trap will probably work fine for another 100 years.....


get one made of pvc and it might even go 200 years....


as long as it isnt letting sewer gasses back out of the trap it has probably worked fine for 100 years....


I just tangled with a s trap today in an old home while install ing a Delta faucet on the lavatory,,,, I took the sink off the wall, changed the faucet and re hung the sink and the new chrome tail piece pipe fell right back into that little old s trap as pretty as you please....its been there for 75 years and will be just fine long after I am dead and gone too.


dont make a mountain out of a mole hill if you dont absolutely have to
(especially in rental properties)


But I guess if you are going to lose sleep over it, then go ahead and turn it into a project. take the easy path.... and forget about ti.

S trap

I'd be happy to avoid another project. Unfortunately the city inspector is requiring a replacement.