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Tapping dehumidifer into sanitary standpipe for washing machine

Posted on 9/21/25 at 9:17 pm
Posted by jlovel7
NOT Louisiana
Member since Aug 2014
23735 posts
Posted on 9/21/25 at 9:17 pm
Can I use this fitting to tap my dehumidifier hose into my sanitary directly? Threaded end would tap into sanitary pipe. Barbed end goes to the dehumidifier hose. Would then put sealant around it + a hose clamp.

Posted by weadjust
Member since Aug 2012
15633 posts
Posted on 9/21/25 at 10:33 pm to
I would use a few zip ties to attach the dehumidifier hose to the washing machine drain hose & skip the barbed fitting. See how it works out. Thats assuming the two hoses zip tied together will fit in the stand pipe.
Posted by T-Jon
Member since Jan 2012
96 posts
Posted on 9/22/25 at 4:46 am to
What material are you “tapping” into? Cast iron. PVC?

Edit: the answer is the same for either material:
Don’t do that

If there isn’t room for the dehumidifier drain hose to be zip tied to the washer drain hose, increase the drain size for the last few inches.

You could also add a hub drain to the standpipe. You have to be careful that the washer discharge doesn’t blow water out of the hub. Also: access panel, don’t double trap, etc
This post was edited on 9/22/25 at 5:05 am
Posted by jlovel7
NOT Louisiana
Member since Aug 2014
23735 posts
Posted on 9/22/25 at 7:11 am to
quote:

If there isn’t room for the dehumidifier drain hose to be zip tied to the washer drain hose, increase the drain size for the last few inches.


Not sure how that would work. The washer drain hose enters the standpipe maybe 3’ off the ground. The dehumidifier drain starts like 8” off the ground and my understanding is it cannot have any rise to it.
Posted by jlovel7
NOT Louisiana
Member since Aug 2014
23735 posts
Posted on 9/22/25 at 7:12 am to
quote:

Also: access panel, don’t double trap, etc


Please go more into detail here.
Posted by jlovel7
NOT Louisiana
Member since Aug 2014
23735 posts
Posted on 9/22/25 at 7:20 am to
quote:

I would use a few zip ties to attach the dehumidifier hose to the washing machine drain hose & skip the barbed fitting. See how it works out. Thats assuming the two hoses zip tied together will fit in the stand pipe.


The issue with this is height. See above but the entrance to the stand pipe is several feet higher than the dehumidifier drain starts at.
Posted by baldona
Florida
Member since Feb 2016
23306 posts
Posted on 9/22/25 at 7:49 am to
You need to add a photo of what you are tapping into for the best help.
Posted by T-Jon
Member since Jan 2012
96 posts
Posted on 9/22/25 at 8:26 am to


Don’t double trap means don’t have 2 p-traps in line with each other. So don’t put a p-trap on a hub drain coming off of a washer drain riser that is already trapped under the floor.

If you are make a plumbing connection like this behind a wall or any indirect connection behind a wall. You should install an access panel for maintenance/problems. Condensed water lines have to be cleaned out regularly. Sounds like you might not be installing this behind a wall.

The 1st reply is still the best if you can install the dehu on a platform above your washer. Details and photos would help.


Posted by jlovel7
NOT Louisiana
Member since Aug 2014
23735 posts
Posted on 9/22/25 at 9:10 am to
Walls are open on one side. It’s in a basement with a concrete slab and I can see the sanitary line running along the floor and then turning a corner before turning out horizontal to the street through my yard. There is no additional P trap below or anything like that unless there is something happening in my yard. There is a P trap at the washer but again all above slab. But I assume that does not apply.

Cannot get good pictures at the moment without rearranging the utility room.

All connections would be accessible via the open walls as we plan to keep the utility room open for a while. Once construction on the house settles after a few years we may close it in. But right now we are need the utility room open to run additional plumbing/electrical/data etc.. to the rest of the house.
This post was edited on 9/22/25 at 9:12 am
Posted by 2 Jugs
Saint Amant
Member since Feb 2018
2297 posts
Posted on 9/22/25 at 8:04 pm to
quote:

Threaded end would tap into sanitary pipe




If you tap this into the washer drain line, your dehumidifier will be flooded with water from your washer.
Posted by TigerCael
Member since Jul 2019
165 posts
Posted on 9/22/25 at 8:54 pm to
If it's a stand-alone plug-in dehumidifier, put it up higher so the drain hose can just go into the open drain next to the washer drain hose. Build a small shelf, or buy an unfinished upper cabinet from Home Depot for $100, paint or stain it, and set the dehumidifier on that.
Posted by baldona
Florida
Member since Feb 2016
23306 posts
Posted on 9/23/25 at 6:52 am to
You can buy pumps for $60 at most, these are used to pump hvac condensate water. Pumps aren’t ideal but for a dehumidifier it’s not really a big issue as it’s more for comfort so it not working isn’t catastrophic.

The easiest thing would be to install this and just pump it up and into your washing machine drain line.


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