My drain pipe in my unfinished basement is close to the ceiling which makes it hard to change things. I know that the drain in my basement is wrong right now and I am trying to fix it. I only have one attachment of ABS (1 1/2") to the main cast iron drain pipe and adding another one isn't really an option. I have a kitchen sink with a dishwasher attached to it and a basement laundry tub pump that all needs to be attached to the same drain. The laundry tub pump says that it does not need to be vented or have a trap. I have posted pictures of two options that I am thinking of. What is the best way to do this?

Option 1

Option 2

  • Could you supply more info on the laundry tub? Does it have an internal trap? A trap of some sort is critically required to prevent leakage of sewer gasses into the house. – Bryce Mar 5 '14 at 23:31
  • I think you'll need a wye and 1/8th inch bend connection where the sink/dishwasher drain meets the horizontal pipe. And, 1 1/2" may be adequate, but I think 2" would be better. Also, it seems like the pump could create a vacuum that might suck the water out of the sink/dishwasher's trap; so, I would add a check valve between the trap and the wye. Finally, just so that if water ever backs up in the drain pipe due to clogging it won't flow back thru the pump, into the basin, and onto the floor I would consider (if the pump won't prevent it) adding another check valve on the horizontal run. – getterdun Mar 6 '14 at 1:09

You need have to have a vent between the washer and kitchen drain and you can't have a running trap in the pipe like that either, I know codes are different all over the U.S. but this is the way we would have to do it according to southeastern builders/plumbing code, been a master plumber for 18 years. Not sure if my drawing is going to post but you need a combo for the ks drain and a combo for washer drain, with a trap and pro vent above the trap on a make shift vent terminated wherever you cab access it in the future. Good luck

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