Toilet empties mysteriously

maddo

Twice in the last two months I have gotten up in the morning to find that the toilet is completely dry. When i flush it, it works fine. I've called the city to see if it's related to the sewer pipes, but they say it must be a plumbing problem. But what could drain a toilet that has the bend in it? It would need some suction. So it can't be just a leak.

Help!
Maddo

joecaption

A plugged up vent can suck it dry. Anyone taking a shower, a load in the dishwasher, or washing machine is all it would take.

DannyT

if you have a clog in the line the line fills with water and when the water drains out overnight it siphons the water out of the bowl. only once in my 20 years as a plumber did i have a toilet that had a leak on the trap and the bowl would empty.

Alan

We had a brand new toilet that did that once. Strange.


To OP :

Sometimes all it takes is a little piece of paper or something to get the bowl to wick out over the trap. No suction needed. Get a glass of water, set it on the counter, put a wet piece of string in it and hang it down into the sink. You will see in the morning that the glass is slowly emptying.

Same effect with the toilet trap. The only reason why it would be siphoning itself out overnight is if something is running while you are asleep (dishwasher or clotheswasher) and you have a venting problem. I would be more apt to go with something partially stuck in the trap. Don't see too many vent problems at least around here.

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Journeyman Plumber

ben's plumbing

it would seem that even a clogged vent would not drain a trap completely it would break trap seal to let sewer gas in then just vent through.....now a crack at the bottom of trap would drain it completely.... or as alan said syphon action causing it to drain.......fill commode with colored water open clean out plug stuff with rag..don't use anything in house for a couple hrs see if water is leaking down stack....this should confirm crack in commode...

TheEplumber

Are you prone to walking in your sleep? Or do you have a thirsty dog?

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maddo

I don't know if I walk in my sleep, of course, but that wouldn't empty the toilet anyway. And I don't have a thirsty dog. But I do think the wicking thing idea or partially blocked pipe might be the answer.

Thanks for you help all! I will wait before calling in a plumber.

maddo

What is the vent and how could I see it to see if it's plugged?

Alan

A vent is a pipe taken off of the drain line (off the top in my jurisdiction) and travels through walls, up the walls, through ceilings, ties into other vents, etc, etc, etc, until it eventually penetrates the roof. These are designed to keep the trap from siphoning itself out, either by use of the fixture in question, or by other fixtures attached to the same branch line.

How to address a plugged vent depends a lot on the way said vent is plumbed. One option is to try snaking down the vent, but again, depending on how said vent is plumbed, you may have a heck of a time getting a snake down the vent from the roof, and getting to the clogged section of the vent.

In my opinion, your easier option is to pull the toilet, check the drain line for a partial blockage, check the toilet bowl for cracks or imperfections that could cause a partial blockage, and check the toilet outlet for a partial blockage. If that finds nothing, it wont hurt to put a toilet auger down through the bowl, and see if you can't push something out. If and when that doesn't work, I would say it's up to you (and perhaps someone who can look at the system) to decide whether it's worth it to try snaking the vent or if replacing the toilet would be a possible solution.


(my most thorough post of the year i think.)

Good luck.

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Journeyman Plumber

maddo

Thanks Alan, I think I'll do all you say. Actually I was thinking of getting one of the new low-flush toilets anyway, so maybe this is the time to do it if checking the vent turns up nothing. (Well I guess "new" isn't the right word to apply there as I think they've been around for quite a few years).

Thanks for your help.