Hello, I have a question about plumbing codes concerning washing machines. I know that the codes forbid that draining hoses be connected to kitchen traps. I was wondering if the plumbing codes also require that anti-siphon devices be used for the draining hose or if there are any other rules regarding backfilling. I live in New Jersey, but other states' codes would be fine.

Thank you.

Anti siphon are not required. Typically the hose end is 30" or so from the trap. The riser end should be 6" above the top of the washer. Problems do arise with pedestal washers that are above the riser, the washer may not ever fill as water will spill over into the drain pipe.

Thanks. I didn't think that they were required, since the back filling would only affect the washing machine not the water supply.

When backfilling happens, could there possbily be something qrong with the machine? Or is it pretty much always incorrect installation?

Hello,

When water backfills from the drain hose into the washing machine, could there be a problem with the machine itself? Or is there just some issue with the installation?

MIN 46. Just add to the existing post, don't start a new one.
How high above the top of the washer is the drain hose? Is the washer on a pedestal? It is normal to get a small amount of water back since there is trapped water in the hose from the pump to the drain. However, it should be less than a quart or two.

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I was wondering if the plumbing codes also require that anti-siphon devices be used for the draining hose or if there are any other rules

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Brian nailed it! The air gap in the stand pipe is the anti-syphon device.

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could there possbily be something qrong with the machine? Or is it pretty much always incorrect installation?

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I'm still trying to figure out your complaint. Is it when the washer stops pumping and the water rubs back from the hose into the sump? Is that what concerns you? Or is it something else? Back to you, Tom