View Full Version : Washing Machine Drain Question

10-23-2009, 09:38 AM
The 4" main drain line exiting my house goes through the wall of my basement 50" above the floor.

My washing machine can be placed within 6' of this drain line.

I am able to replumb the main drain line (adding a Y) to add a direct drain for the washing machine, but is there a way to do this that would be code compliant as it releates to the various stand pipe/trap measurements necessary to meet code?

So basically I want to use the washing machine's pumping ability to get the water above the 50" level and then allow gravity to do the rest of the work from there...so everything indicated in Terry's infamous photo would need to be above 50" off the floor.

Doable or do I have to keep things the way they are where I currently am pumping the discharge into a sump it and them a sump pump pumps it up into that main drain line?

Doherty Plumbing
10-23-2009, 07:04 PM
I don't know about your code specifically but the BEST way to do it is to do it with a sump pump because then you can install a check valve. So when your sewer main backs up your washing machine won't be full of doo-doo. :D

A lot of DIYers just do what you described and run the washing machine hose up to the height of your sanitary building drain and wye into it. But this isn't the best solution for the reason I described above.

10-24-2009, 11:51 AM

Thanks for the reply...we are on septic (not that it couldn't still back up), but the larger part of this project is to run new 4" PVC from the house to the septic tank to replace the original cast iron pipe currently there. So I'm fairly comfortable taking the risk of going without a check valve since I'll have removed the possibility of my sewer line being compromised by caving in, tree roots clogging it etc.

I'm also going to build a small platform to put under the washer to make sure I'm not working its pump too hard since I'll need to get its drain line up a bit higher than it is now.