New dishwasher install

Hi All,
I am planning to install a new dishwasher in my kitchen. The only place I have space for one is at the other end of the kitchen from the sink, so it can't drain into the sink drain. I would like to drain it into the 4" main drain line in the basement, which is directly below where the dishwasher would go. I've looked at quite a few threads on this and am starting to get it, but I wanted to run a couple options by you folks.

I'm attempting to attach a sketch of the options...

Option 2 is the one I'm inclined to go with - using a loop vent to go back into the main drain line. However, I don't know if the way I have it drawn is the right way to do it.
Option 1 replaces the loop vent with the AAV, installed above the dishwasher
Option 3 has an AAV in the same drain line as the dishwasher but connects below the trap. This is one I saw on another website and frankly it doesn't make much sense to me.

Any thoughts would be much appreciated.
Thanks!

I don't think any of those would pass code. You need an air gap to separate the DW drain from the septic system. If there was a backup, you'd possibly get sewage back into the DW on any of the choices.

You can extend the line from the DW to the sink. Since it is pumped, the distance isn't a huge issue, but the access could be.

Hi Jim,

Thanks for your thoughts. Could I not install an air gap with any one of these configurations if the dishwasher I install requires one?
I don't think I can extend the drain line to the sink because I'd be over the maximum drain line length spec'd by the manufacturer (generally < 12 ft as I understand it)

If you installed an air gap, probably. If it is quite low and there was a backup, though, you might end up with sewage out the air gap, but it would be better than into the DW! that's the hassle with hiding things like that. Into the kitchen sink, you'd likely notice it! The drain should also have a vent line. This has been discussed recently, so use the search function to see what has been said.

Air Gap. No moving parts, best afforded protection from backflow. It is strictly enforced on the commercial side of the equation, no reason it shouldn't be on the residential given the less chance to affect the number of people involved.

I have looked at quite a few of the old threads. I'm still confused about the loop venting though. The other examples I've seen show the loop going back to a vertical stack. I don't have access to a vertical stack, so I've drawn it going back into a sloped run in the basement. Would this work, or should I be doing an AAV like I tried to show in Options 1 and 3?

Thanks for the help!

1 is wrong because you don't connect a vent above the trap

Generally, you can't connect a pumped drain to an AAV vent.

An air gap by definition would have to be above the top of the countertop.

quote; 1 is wrong because you don't connect a vent above the trap

?????WHERE would you connect it? #2 would pass if you have a novice inspector who would not notice you do not have a "foot vent". #3 is completely wrong because it creates an illegal "S" trap. With any of these you need a countertop air gap to keep the water inside the machine and provide the proper antisiphon/backflow protection since you would be connecting directly into a waste line, (a "high loop" would NOT provide the necessary protection in this case).

I just looked up a "foot vent", glad I know what that's called.
Yes, with my plumbing there is no way to put a foot vent in without lots of destruction. We don't have building codes where I live so no worries about inspections. I guess the question is just whether a loop vent with a missing foot vent is better or worse than an AAV.

You say there are no building codes where you live in Vermont. I find that very doubtful, but even if true, there are reasons why codes exist. Codes are not in place to make thing difficult or make jobs for inspectors. They are to insure buildings and what goes in them are safe. Certainly codes can make retro fitting existing homes with plumbing difficult and costly, but those of us who undertake DIY tasks that we have no training in can screw things up through our lack of knowledge. This forum exists to help us novices through at least some of these tasks with acceptable work. It is not the purpose of the forum to help DIYers circumvent plumbing codes.

If there are no speed limits, does that mean you do NOT have to drive slowly sometimes? The codes have a function, which is to produce a safe plumbing system. IF you do not have anyone who enforces the codes, that does NOT mean that the reason for any restrictions has been nullified. Any drain condition that caused a problem with an AAV, would also do it with a "loop vent" with, or without, the foot vent.

hj said:

quote; 1 is wrong because you don't connect a vent above the trap

?????WHERE would you connect it? ).

Click to expand...

His # 1 shows the AAV on the dishwasher side of the trap. Is that where you would put it?