Clogged utility sink

Old 05-13-24, 05:47 PM
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Clogged utility sink

First water/ sewage was backing up from main basement drain when it rained hard and used water in the house simultaneously . We cleaned our septic tank and had the main pipe (starting pipe from leech lines) coming from septic tan fixed. Now since then no water/ sewage water backs up from the main drain but comes up the utility sink, but only when we use any water in the upper level. Whether itís raining or not. Where is the clog ? Iím trying to figure it out and snake it out myself instead of paying someone again.
Old 05-13-24, 08:03 PM
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I think it's difficult to say for certain without seeing the plumbing, but I suspect your wastewater normally flows along the main line, past the utility sink pipe joint, then past the basement drain joint to the septic. If so, you have an issue somewhere between the utility sink pipe joint to the main line and the basement drain / cleanout pipe joint to the main line. Waste water flows through the main line but can't exit due to the blockage so it backs up. Since the blockage is before wastewater reaches the basement drain, the wastewater backs up to the utility sink. I suggest getting a professional in to fix it as the blockage may be more than a clog.

Here's a picture that may help you. Note the drain / main line joint and utility sink / main line joint. I suspect the blockage is between them. A wastewater system is not pressurized. Wastewater flows downhill until it can't do so, then backs uphill along a route of least resistance, in this case the utility sink pipe.


Last edited by PJmax; 05-14-24 at 01:04 PM. Reason: resized pic
Old 05-14-24, 05:28 AM
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I would snake the main drain line between the septic tank and house. Then you can check/clear branch lines like the one heading to your laundry sink.
Old 05-14-24, 11:41 AM
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Sounds like you have a non-functioning check valve in the utility sink drain.

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