Check valve needed? Water on floor of basement.

[LarryLeveen]

Moved into a new house several weeks ago -- have been using the plumbing and appliances (dishwasher & washing machine) as one usually might. Yesterday, I saw there was water on the floor of the basement. I did also see some shreds of paper-like material on the floor -- perhaps it was in the pipe and came out with the water.

The previous night, the bath had been used, and also the dishwasher. The clothes washer was NOT. What I think might have happened was that while the tub was being drained, the dishwasher tried to drain as well. Since the tub is on the second floor and has a lot of head compared to the dishwasher's pump, the water backed out and came out the LAUNDRY machine's drain.

I have a vague recollection of faintly hearing an odd noise, like a pump running. Since it is a very new house, I thought maybe it was a new/weird fridge or dishwasher noise. Perhaps, though, it was the sump pump running. I can't exactly tell how the sump pump drain connects to the larger sewage outflow pipe, so I don't know if it just sent water around in a circle -- out the laundry drain and back onto the floor -- until the tub had finished draining and there was capacity for it to successfully pump out the water on the floor.

QUESTIONS:

1. Why did this happen? Was there a check valve missing or malfunctioning? How can I tell?

2. Any other thoughts on diagnosing what happened and what to do about it?

Thanks.

 

[Reach4]

Maybe tie a paper towel or tissue around the standpipe. That would be to record signs of the washer standpipe overflowing.

Could it be a sewer backup through a floor drain?

You should normally not have a check valve in a gravity sewage line.

Are you hooked to a city sewer?
Do you have overhead sewers? If you don't know what that means, search it out. If you have overhead sewers, there will be an ejector pump to handle the basement sewage. In that case, there is a check valve in the line pressurized by the ejector or grinder pump. That pump is in a sealed and vented pit/basin. If you don't have overhead sewers, then you should worry about a city sewer backup.

The basement should have a sump pump also. That term is usually used for a pump that handles ground water.

 

[Sponsor]

 

[Terry]

1st, Do you have a pump down there? That would change things.

If it's the dishwasher and tub draining, then perhaps the washer drain is backing up. New home? Or new to you?

 

[LarryLeveen]

Ah, update:

The tub just got used by itself and water is on the floor again. I guess the first time it got used, we just didn't notice. Also, the washing machine standpipe is dry, so the water seems to have come out of the drain that the sump pump hose goes to. That is, it is backing up, from the wastewater pipe from upstairs to the junction where that meets the sump pump. Yikes! What should "we" do?

I say "we" because we rent, but I want to know what the heck is going on because it is our deposit and our stuff that can get ruined. Also, because I am curious, and I really respect the people on this forum (been a member for a while, but haven't posted in ages).

Advice?