Hello, due to corrosion between a galvanized pipe and a cast iron pipe I have had to plug the original drain fitting and reroute two small sink drains from a main line to a 2 in un-vented clean out line. I plan to vent the pipe with an air admittance valve, however it may take me few days to install the valve. My question is how concerned should I be that the drain is currently not vented and won't be for two or three days?

Tell us what you mean by


2 in un-vented clean out line

Do you mean to 2" clean out in the main stack?

If the sinks are close enough to the main stack to have been vented through the main stack, moving the drain to the clean out may have made the sink drains unvented. If the sinks were not close enough to the main stack to be vented by the stack there will be a vent for the sink and rerouting the drain will not have made them unvented.

If the sinks are unvented you risk the traps being syphoned dry and get sewer gasses in the house. As a temporary measure you could just close the drains after each use.

As a permanent fix why replumb? Why not cut the galvanized pipe back where it is solid, remove the part that goes into the cast iron (presumably the stack) put in a gasket and reconnect with PVC using a shielded rubber coupling to connect the galvanized iron and the PVC.

The 2 in clean out line which I have re plumbed the 2 sinks too was a dedicated clean out only, it had no drainage flowing through it and did not require a vent stack... previously... it connects directly to the homes main sewer line underground and is about 2 feet away from the homes only vent stack (it's a small home)...

the clean out line was simply easier access, the sinks are almost back to back in different rooms and there is no vent stack, currently... pending installation of the air valve

The galvanized pipe was was rotted where it threaded into the cast iron main line and subsequently broke off. To access and repair would have required cutting new holes in the wall, which I am not willing to do at this time, so I plugged it and re plumbed everything using PVC (from an access panel created for a older plumbing issue)... the permanent fix suggested was done less then two years ago by a professional plumber, back when I still carried a home warranty... eliminating the cast iron and galvanized pipe from the equation (to me) will put the issue to bed for good...

in the future I plan to remove the cast iron and replace it with PVC... most likely to be done when the kitchen is redone... what I don't understand about my home's sewer line, is that only the main vent stack is cast iron, everything else is modern PVC...

My question is how concerned should I be that the drain is currently not vented and won't be for two or three days?Put your mind at ease. The sinks will vent through the traps, I like the fact that you realize that this is only a temporary repair and that you plan to do it right in the future. Good luck, Tom