Island dishwasher drain

[Todd McManaway]

wanting to know how to drain my dishwasher which is located in an island across from my kitchen sink. It is not possible to drain it into the disposal since i would have to go underneath the floor and then back up into the sink cabinet. It sits on top of a cellar so there is access to drains,electrical and water. I thought about a stand pipe since i read on other posts that you can't drain it into a drain pipe by itself. I would also attach a p trap to it before going to the main drain. Any help would be greatly appreciated.

 

[Sylvan]

Not only does it have to go into a trap that is vented there should be an air break (air gap) to prevent any possibility of any type of back flow

 

[Sponsor]

 

[Todd McManaway]

Not only does it have to go into a trap that is vented there should be an air break (air gap) to prevent any possibility of any type of back flow

Not only does it have to go into a trap that is vented there should be an air break (air gap) to prevent any possibility of any type of back flow

Would the loop of the dishwasher drain suffice for the air gap and would tying it into the main drain for the sink under the floor be enough for the venting.

 

[Todd McManaway]

Would the loop of the dishwasher drain suffice for the air gap and would tying it into the main drain for the sink under the floor be enough for the venting.

I dont know how i would vent it to the roof since it sits in the middle of my kitchen. No walls close by to use. I thought about this saw it on here from a previous post. Would this be okay? Any help or thoughts. Thanks.

 

[Reach4]

Any help or thoughts.

The AAV has to be changeable, so you would not mount it at the top of the cabinet. Four inches is minimum.

 

[Jeff H Young]

My code UPC would still require an air gap but IPC may not but the picture is a common way of plumbing DW waste out side of CA but don't know if that is current or legal in your area

 

[Todd McManaway]

Thank you very much for the help and advice!

 

[lugan55]

I'm sure this has been answered already somewhere but looking for opinion on which of these 2 options may be better for a dishwasher in a kitchen island WITHOUT a sink...either AAV or high loop...I then have 16' run across the basement ceiling to tie into drain.

 

[Reach4]

From a functional point of view, the one with the AAV would be better, because it has a vent. If you had a proper island vent with a vent pipe, that would be better than either of your drawings, and would be more likely to meet Toronto code.

https://terrylove.com/forums/index.php?threads/air-admittance-valve-above-the-flood-level-rim.14452/ says you cannot use an AAV. It does have a diagram of an island loop with a vent.

https://terrylove.com/forums/index.php?threads/aav-valve-for-washer.70769/ says an AAV is OK with at least one plumber as a last resort, but there was no citation of code.

 

[lugan55]

So something like this would be best?

 

[Reach4]

So something like this would be best?

That is good, but seems incompatible with an island.

 

[lugan55]

That is good, but seems incompatible with an island.

We've decided to move island against an existing column. This column will now be on one corner of the island. I will expand this column to encompass the vent pipe and send it through the attic above and through the roof. What size pipe for drain and vent?

 

[Reach4]

We've decided to move island against an existing column. This column will now be on one corner of the island. I will expand this column to encompass the vent pipe and send it through the attic above and through the roof. What size pipe for drain and vent?

Ontario code may allow smaller, but 1-1/2 vent and 2 inch drain is liked everywhere. If 1-1/4 vent makes your column easier, then check the code. If you want to go smaller than plastic, you could save a little space by making the vent out of copper. Copper is more expensive.