How to tell apart clogged vent vs. clogged sewer?

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Old 09-26-18, 10:58 AM
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How to tell apart clogged vent vs. clogged sewer?

How-to website list the SAME symptoms for a clogged vent and clogged sewer (toilets gurgling, sinks draining slowly). Is there a way to tell the two problems apart?

The toilets in 2 of my bathrooms gurgle and drain very poorly-- but ONLY at night! They do OK during the day. Shower/bath drains show evidence of backing up (visible junk on tub floor). There is no visible problem with bath & kitchen sinks. I looked down the vent pipes from the roof, and there are no visible clogs.

Thank you.
 
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Old 09-26-18, 11:45 AM
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There really isn't a definitive way short of sending a camera or drain snake down the line to find the clog. Generally a clogged vent may cause fixtures to drain slowly or gurgle but I've never seen it cause a back-up. Plus, in my experience 99% of the time it's the drain line that's clogged.
 
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Old 09-26-18, 12:07 PM
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Pilot Dane -- thank you!!!

(Ugh -- I was hoping it was the vent, which I can try DIY ... I don't think I can DIY the drain line.)
 
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Old 09-26-18, 01:39 PM
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Not that big a difference. One is on the roof and the other is at ground level. Ground level seems safer to me. You need the proper kind of snake for either/or. A long thick tape style snake is meant for main line sewer work.
 
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Old 09-26-18, 02:55 PM
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The implication is that you've been able to get up on the roof and peer down the vent . . . . is it possible that you'd be able to pour a gallon of water down the vent while someone else watches what transpires inside at the same time ?

They could watch the most troublesome fixture(s).

That procedure would eliminate the possibility of a vent obstruction (I think ?).
 
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Old 09-26-18, 05:28 PM
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The toilets in 2 of my bathrooms gurgle and drain very poorly-- but ONLY at night!

Clogs cant tell time, if they are clogged then they are clogged, if there is a difference then it has to be something else!
 
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Old 09-26-18, 06:01 PM
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You could always put a garden hose down the vent to test for a clog.

The 'only at night' thing is weird. What other variables happen in your system at night. Im guessing that is when everyone is home and that is when the most water gets used. Do you have a septic tank? could be clogged. Partial tear in your sewer? you could have a sludge buildup that allows some but not a lot of water through. Then you would only see a backup during peak flow times.

Run a lot of water and watch those toilets. I agree you likely have a main line clog or problem of some kind.
 
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Old 09-26-18, 07:47 PM
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If you are on city sewer, the line at the street is also a shared line with many other houses... there could be a backup on the city's part of the line as well, which can cause your lines to run slow. Everyone in the neighborhood may get home from work at about the same general time and showers and starts doing wash, and taking baths and so on. So yeah... it could CERTAINLY be time related.

The order of things is to have your tub drains snaked... toilets pulled and snaked... have your main line snaked the cleanout as far as they can go. Sometimes they find tree roots (that's your problem). If they snake it and the problem persists, take the proof from the plumbers findings and call the city. If back flow from the city sewer lines is a potential problem you may want to invest in a backwater check valve. No one wants their basement flooded with other people's wastewater, let alone their own.
 
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Old 09-27-18, 05:43 AM
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Time of day back-ups generally have to do with water usage in the home. If the clog is far away from the fixture the pipes can hold a lot of water. So, it may take a lot of use to fill up the pipes for a backup to be visible. Maybe in evening you are using more water preparing dinner, washing dishes, giving kids their baths, taking showers.
 
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