Plumbing a Dishwasher

[hadespuppy]

I'm getting a dishwasher delivered in a few days, and there's obviously been one in the space before, but I suspect that the plumbing is incorrect. You can see the hot water at the back, which should be right, but it's the drain that has me concerned. Every diagram I have seen has the drain from the dishwasher going into the sink drain between the

Comments

[runonthesun]

I've actually installed a a few of dishwashers and I've redone an entire kitchen by myself. The one thing I never messed with is hooking up drains. Unless you really know what you're doing, they tend to leak and they also can be prone to sewer backups if not done right. It's worth the piece of mind to pay a couple hundred dollars to have a plumber come out and correct an improper layout - you would probably end up doing it when you eventually sell the place anyway. What you have isn't to code and the black vinyl pipes aren't as intuitively easy to fix and leak-proof as you would think.

If there's a second trap, then the second trap for the dishwasher should be on the sink side of the main trap, not on the sewer side of the main trap. The normal dishwasher drain line should have a dry loop in it that's hung above the trap so that sewage from a sink or trap or sewer line clog doesn't siphon into the dishwasher while the dishwasher is running (and pollute your half-clean dishes without you knowing it).

Having said that, IF you were going to try to mess with this, you would want to get yourself a piece of flexible dishwasher drain line and loop it above both traps before connecting into the second trap, and you would probably want to actually remove and straighten the gap where the second trap is.

[revchris]

I"m not sure about whether or not there are code issues with this - each device discharging into the main sewer line has its own trap; that's the kind of question you should contact your local building inspector about.

There also may already be a dry loop - on my dishwasher it's behind the dishwasher and not in the sink space.

The one thing I see that I would probably change is the tee where the dishwasher comes in. I would have used a wye rather than a tee for better flow and less back pressure on the dishwasher drain when the sink drain is flowing.