Minimum height for washing machine standpipe

10 years ago

What's the minimum height for a high efficiency front load washing machine standpipe assuming the P Trap is no higher than 12" from the Floor? General plumbing rule of thumb seems to be 36" from floor. I'm also reading suggestions of 18" above the trap weir as a minimum. Additionally I'm seeing that the minimum height should also be above the maximum water height in the washing machine drum to prevent siphoning. With older top load washers I can see where a higher water height would necessitate a higher standpipe and hence the old safe 36" height rule of thumb. But with newer front load machines it seems the water height is now lower especially if the machine is not on a pedestal. So if my trap weir is at 12", my maximum water height in the machine is say 20", can I put the standpipe height at 30" or can I get away with it being even a little lower? Reason I need it to be no higher than 30" is so that the entire standpipe box surround which includes the water supply lines is below the height of the counter that runs above the machines. Thanks.

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Comments (4)

klem1
10 years ago
If you didn't get installation instructions and owner's manual with machine I suggest contacting manufacture to ask for manuals.
Amy Bernard
Original Author
10 years ago
There is a recommended placement, but we're trying to determine whether we can deviate from that without issues. I'm hoping someone with plumbing expertise can weigh in and help us out!
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Vith
10 years ago
last modified: 10 years ago
Water can only go through the trap so fast depending on the pipe size, and needs the weight of more water on top to push it through that fast. That is why they recommend a certain height so it doesnt overflow. I dont think any of us would be able to tell you it will work fine with certainty. You will have to experiment. If it works, great, if not then it needs to be higher. Run a test load with nothing in it and have it fill and drain. Watch for overflow, be ready to stop the drain cycle if it happens. Something that may help you is an air gap insert at the top of the standpipe.

I dont exactly understand why you cant have the pipe go up higher inside the wall behind the counter. Is this not an option for some reason? If you can reach it, you wont need an access panel.
klem1
10 years ago
Vith,that's an exelent explaination in layman's terms and I agree 100% with your observations.