Cap Dishwasher Drain Advice (Johnson Tee?)

[bwolfgra]

I am replacing my dishwasher and found that the drain line goes back into the wall behind the dishwasher. I'm told this is probably a "Johnson Tee" configuration, but I can't find the expected vent related to it on any of the walls inside or outside of the house, so it could just be a tee into the drain line.

I had a plumber look at it (externally, we didn't open walls/remove cabinets), and he said that it was probably connected back to the drain, because whoever installed it didn't want to go through the stone outside the house or back into the kitchen. His advice was to leave it be, because it had been in place for years without problems.

My new dishwasher requires a larger drain line anyway, so I am going to run that through an air gap to the disposal, but I'm not sure the best method to cap off the old drain. Since it is a drain and there wouldn't be high pressure against it, could I just replace where the drain hose is currently connected with a rubber cap or sharkbite style fitting? I don't want to start opening walls to search for things that may or may not be there.

Thanks.

 

[Terry]

It should be capped off. Any pipe leading to the waste and vents can allow either water or sewer gas back into the home. Neither one is good.

 

[Sponsor]

 

[bwolfgra]

That makes sense. I'm definitely going to cap it. I just wanted to make sure there wasn't a reason why I couldn't just remove where the hose is currently connected and cap it right there where it is accessible with one of the push on fittings, rather than making any more modifications than necessary.

 

[Terry]

The push-on cap works well with 1/2" copper.

 

[bwolfgra]

Thanks, Terry.

I’m going to get the hose off, confirm copper, and then attach the right cap. I’m just glad I don’t need to start cutting the wall apart.

I appreciate the advice and happy to have found this forum. Thanks for a great resource.