Hello fellow inspectors. I recently inspected a new construction home. I advised the buyer that the laundry area was lacking a proper washing machine drain, “no standpipe or trap between main sewer line and washing machine” and that it could be an added cost when installing the washing machine. The builder responded and said that the backflow check valve is compliant for the washing machine drain. I had never seen that used as a washing machine drain, and I did not see a trap between the check valve and the main lateral sewer line. I just haven’t seen this type of check valve used as an opening for a washing machine drain. Hoping someone could steer me in the right direction. Thank you!
Morning, Christopher. Pleasure to meet you.
Backflow check valves are common. No worries.
If that is the standpipe trap then there is a problem.
Looks like that horizontal drainage line to the sewer is above the basement floor. Hmmm.
Is that the laundryroom in the basement?
If so, the laundryroom is not completely roughed-out.
No vertical drain pipe? Waste Water doesn’t flow upstream…
No standpipe.
Thank you for your response. To me it looks like there’s no trap between that check valve. (That will be opened) to allow for the hose and the main sewer line. Yes the washer dryer would be on the basement floor. The washer would hook into that check valve and drain to the right and down to lateral line.
I’d be concerned about overflow. Depending on the washer, the discharge can be very sudden and forceful. Everyone of those pipe bends is a restriction. I’d call it out as a defect.
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To me, it seems that if there is no drainage system in the basement floor, that at a minimum a greywater sump system should be installed to pump the greywater up and into the waste water system.
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I’m assuming the washing machines themselves have a sufficient pump to get wastewater to this height. If i really breakdown the question- can a washing machine be attached directly to this check valve instead of a traditional standpipe and p trap? I just can’t seem to find any information where that is done. Even ChatGPT couldn’t help me. Lol
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Unless your local AHJ has a provision in the local plumbing codes for it, the builder could be full of 
. Check with your local AHJ. Around here that setup wouldn’t be allowed.
Agreed. I’m not seeing how it could work even if there’s an inlet in the top of the check valve.
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My thought exactly, and by design, I cannot comprehend in any manner how it would properly function!
Trust me… If I am wrong in this, ‘Marty’ will be more then happy to let us all know!!
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I’m with Jeff. It’s a no go and an unnecessary restriction in the drain. It’s simply not needed.
If the builder is planning on modifying the check valve for a an additional laundry machine drain that’s not correct either. If the laundry drain is below the main sewer as it exits the home, an ejector pit will need to be installed.
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If a check valve is installed, something is not installed properly. It is a worry. The only time you will see a check valve installed is if the building drain is installed lower than the manhole cover at the street.
Of course I’m not talking about a check valve that keeps water in a drain pipe so a sump pump or ejector pump doesn’t cycle all day long. That’s different a check valve. A check valve on a laundry drain is ridiculous.
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There is a stand pipe on the left of the trap but a little high…
Makes me wonder if the original plans were to have the laundry room on the first floor, not the basement.
Here’s my WAG…
Pipe on left is a Shower or Tub drain…
Pipe on right of valve is the Vanity sink drain…
Pipe on far right is WC drain…
The Valve is installed to mediate the rush of water from the Shower/Tub, and has nothing to do whatsoever with the clothes Washer.
I see nothing in the (limited) photo that relates to a Washer Standpipe or other Drain.
Personally, I would expect to see a Utility Sink installed, and the Washer drains into it, and the sink drains into the Sump pit or other setup.
I don’t see the pipe on left of that trap going through the floor. My guess is that there is a gap on top of that pipe for the washer, but that picture could be playing tricks.
I suspect you are seeing the optical illusion created by the Blue PEX line running in front of the pipe at the insulation level, making it appear that the pipe has ended.
Zoom in and take a slow look.
Creative setup…
Reminds me of the possibilties in this thread!
Well…according to GE, they can pump 8 feet high, somE models 5 feet…so if the check valve is swapped out for a stand pipe…then it could work?
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That’s what I would recommend. The washer can pump it up to that height. At least this is new construction, so the occupant has time to see how the current setup works and can request repair within the first year. Could also just add another stand pipe to one of the horizontal runs, which would end up with less vertical height than replacing the check valve with a stand pipe.
So do we install based on one manufacturer or follow a standard? Ever wonder where that dirty 8’ of water falls back to once the pump shuts off?
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