We have two toilets in the house, for some reason one of them loses the water from the bowl on an irregualr basis. It seems to be when there's a change in weather however, the problem is that the water level goes below the trap and then we have the sewerge smell rising into our house. Flushing immeidately solves the problem as the water is then back covering the trap. The catch is, this toilet is in the ensuite, there is noting worse than waking up to a sewerage smell wafting through the bedroom!

So far we have added a vent to this toilet as it originally didn't have one but this hasn't solved the problem. Like I said, it's irregualr so may happen heaps for a while and then not happen for months and I cna't prove it but it does seem more often when the weather is changing. Still we need a fix please because the smell when it happens is awful.

Well your not imagining things and it does likely happen when the weather is changing due to the diference in pressures between the house and outside.

It won't happen with the window open.

The Studor vent here may help: Automatic Venting Valves

A cracked toilet will also do it, but it won't be that intermittant.

How the drainage system is arranged MAY also do it, but that should not be weather related.

Ron, (KISS) hit on just about all that could be causing this.

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So far we have added a vent to this toilet as it originally didn't have one but this hasn't solved the problem.

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I keep coming back to the vent.
Therre are only two things that would cause you to lose enough water out of the bowl to break the trap seal. 1) if there were a crack or a factory defect that allows the water to drain out of the bowl.**or** 2) the vent's not doing its job and the water's being suctioned out.
If you're thinking weather conditions, (Please explain what the weather does to cause this. Does it get colder? Hotter? Rainy? More windy? What??
Ron mentions a open window.

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Well your not imagining things and it does likely happen when the weather is changing due to the diference in pressures between the house and outside. It won't happen with the window open.

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If a there's a change in atmospheric pressure in the house why aren't all trap seals affected? And it would take a lot of atmospheric pressure to force a toile bowl to lose its entire water seal. Your ear drums would be popping.
I keep coming back to the two things that would cause this. Well, the bowl can't be cracked because it doesn't do it all the time. That leaves just one thing. He suggested installing a AAV,( air admittance valve). Looks like Ron and I were thinking along the same lines. What if the vent that was just installed was hooked up wrong somehow? I think installing a AAV's a dandy idea. This would ,indeed, prevent any water being siphoned out of the bowl either through atmospheric pressure or faulty venting. Good luck and please keep us informed. Tom

Change in weather is probably defined as 0-48 hrs before rain.
If you have two toilets and one is on a lower floor that the other, bet the one on the higher floor is affected.

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Originally Posted by KeepItSimpleStupid

Change in weather is probably defined as 0-48 hrs before rain.
If you have two toilets and one is on a lower floor that the other, bet the one on the higher floor is affected.

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In over 50 years out in the field, both up North and down South I have never heard oif a weather change suctioning the water out of a single fixture trap while ignoring all the others. And why a toilet that has much more volume in its trap then say a lavatory? Please explain to me how this could happen. You're never to old to learn and you seem so certain that this could really happen that perhaps I've been missing something all these years. Sooooo!
Educate me! Regards, Tom

OK Tom, my explanation:

Let's start with some observations:

I've seen the condition I referenced a few times where the water level in a upstairs toilet changed and the down stairs did not. I've also seen water in the toilet bowl jiggle or pulsate.

I do know what is considered a "weather change" because I am affected by them. I did some research on my own looking at the second derivatve of barometric pressure vs time. e.g. how quickly the barometric pressure is changing. I also know that weather has 7 phases. So, I know the definition of a weather change.

You know about sump pumps and head and you also know that as the pipe diameter increases the pump has to deal with less head. (.44PSI/ft). Well air also has to deal with those same frictional losses and I think the difference in the vent from the basement to the first floor is about 1/2.
This also says that the larger pipes are easier to move. Lbs/square inch of opening. So, this says that say a 3" diameter pipe and a 1.5" diameter pipe will need ((3/2"-1.5/2)^2), the 1.5" pipe may need 1.75 x more pressure to displace the same amount of water.

Amount of water is immaterial, the pressure on both sides of the trap should be zero. If it's not, water will move.

So, therefore due to friction losses and the lengh of the stack, the displacement due to delta P can be different. Larger pipes are more affected than smaller pipes because smaller pipes have greater frictional losses.

So, what can exert a delta P.
Pressure in the house different than outside.
Now that you made me think a bit, we could be acted on by three pressures. Vent, house and sewer.

Everything being equal, vent = house = sewer = 0.

The pressure in the vent CAN change faster than the pressure in the house.

Wind and atmospheric pressure I think are two variables. Far fetched is the aerodynamics of the roof(s). i.e. stack height too low.

What we overlooked though is the possibility of negative pressure in the sewer. I think that can happen if the sewer is damaged and suffers from sewer overload due to too much water infiltration in the pipes. Same thing might happen, but the toilet closest to the sewer could have a lower level.

Comments, criticizums, does it make any sense at all?
I think that is true.

In this process, I think I added two more posibilities: sewer overload, vent stack too low.

So, that being said, I'd like to know which toilet is affected? Upstairs/downstairs/same floor?

Hi Everyone,

Thanks for your feedback.

Firstly, both the toilets are on a ground level. The one affected is the closest one to the septic tanks. It joins into the line that comes from the other toilet.

Now, as for weather changes, I would say it mostly seems to happen during a weather change heading towards rain but I really couldn't fathom why the weather should have had anything to do with it, however, having lived here for 5 years now it did seem to be pattern.

The vent was only added a week ago when it was thought that was the reason as this toilet didn't have one, however, we have lost the water twice in the last week so would seem this isn't the problem. Having said that I closed the window about a week ago due to the bad weather that came in so I will re-open it now and see if that makes a difference. When we lose water it will be within a couple of hours of having flushed, we know it refilled but then it goes. The other toilet has lost water previosuly before however, this has probably happened to the other toilet only twice in five years, whereas the toilet I am talking of loses water probably 10 to 15 times a year. When it happens, it happens suddenly, it's not a slow loss, it's gone within a couple of hours. Yet the rest of the year the toilet is fine so don't think it can be a crack or anything like that.

It's just becoming very fustrating!

But if this were so and atmospheric pressure can suction trap seals out why isn't every house in the nation affected by the same thing. And why, after 50 years, am I first hearing about it? Let's hear for the other experts. You guys ever run into this situation? Certainly there's a pressure differential when a strong wind blows over a roof vent but to suction the trap seal out 0of a toilet bowl? Do you realize the amount of wind force it would take to do that? Right now, as we speak, I am experiencing a hurricane, (Fay) as it passes by my area. I see the toilet level "bounce" a bit but I haven't lost any of the seal. I still want to know. Why suction out a toilet trap when a lavatory or a tub/shower trap has much less volume to be moved then a toilet bowl. I'm still confused and in the dark. Perhaps it's simply old age and brain lock that prevents me from understanding. Regards, Tom

Tom:
Any possibility the septic system needs to be pumped out?

Crazymum:
When was the last time the septic system was pumped out?

Hi everyone...

You know I just had to pop in and offer up some thoughts... ;)

I live in New England and we get some absolutely crazy weather up here.. including hurricanes and microbursts... and I have certainly seen water bobbing in toilet bowls... but just like Tom I have never seen anything related to weather siphon a toilet bowl of water once... never mind 10-15 times a year.

Crazymum... tell us has anyone actually lifted the toilet off the closet flange and looked inside the base of the bowl to see if there is anything that has attached itself to the inside of the bowl and is now actually SIPHONING the bowl via capillary action..

Here, if floss or mop strings or anything like that (tampons/tampon strings) got caught up inside the trap of the bowl it could effectively drop the level of water in the bowl by water climbing up the string/floss, etc. and over the trap and falling by gravity into the drain pipe. Now this I have seen a number of times over the years.

Then, you ask, why is it not happening all the time? Well, I'd answer that it all depends on exactly what is getting hung up inside the bowl and if it is getting moved without getting loosened and then siphons the bowl sometimes but not others. Maybe the inside of the toilet trapway is roughed up and catching bits of paper/floss enough to siphon the toilet occasionally but not to clog it (a little more far-fetched)?

Crazymum... if toilet bowl has not been lifted I suggest you lift the toilet and see what may or may not be caught in the bowl/base of the toilet and let us know what you find (if anything).


Have good day all...

MARK

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Fascinating discussion! But how would the septic tank being full cause LOWER pressure in the septic tank?

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Good question. A full septic tank would produce back pressure which is the opposite of vacume. I still keep coming back to the vent issue. If the AAV was faulty water could be suctioned out of the bowl as a disdharge passes the toilet. I realize this is out in left field but then so is opening the bathroom window so you don't lose all the water out of da bowl.
Ron, I swear I'm not trying to "bust yo chops". This explanation is new to me, I thought in over 50 years I had run into most everything. If there's something out there I haven't been exposed to I want to know about it. This can't be something new, atmospheric pressure's been around for a long time. My big burning question is why haven't I run into this complaint before
Either out in the field or on any of the Q&A sites I've been on? Regards, Tom
I just read Marks post. (Smacks head!!) I gotta be getting old. Haven't had a capillary action complaint for many moons but I should of snapped to that as a possible explaination but the atmospheric pressure thingy had me fascinated.
Thanks Mark,

I agreee that this is a very fascinating discussion. The tampon thing is very interesting. I guess that all you really have to do is create a siphon and poof, and the water disapears. So, I suppose, this is a plausible explanation.

What makes this interesting is ALL the water is missing.

True, I can't really figure out how the pressure would be lower in the septic tank either. It's ventet and the bacteria will produce gas raising the pressure. I can see a clog that eventually breaks loose cause a single drop in pressure.

I guess it can't hurt to run a closet auger in the toilet and if that doesn't work, pull it and inspect manually.

Hey, in the worst case, you can switch toilets to eliminate that.

Bustin' my chops are fine.

Let's hop there is no storm water flowing into the septic system from the gutters.

Interesting read:

http://www.fofweb.com/Onfiles/SEOF/S...ments/5-48.pdf

That's what I am tallkng about exactly. Actually looks like the same article I was provided with in plumbing school... ;)

Good find!

It will be interesting to hear what crazymum has to say. Nothing seems to add up here. I have a problem with KISS's atmospheric pressure theory if only because I've never run into it before, but weather seems to affect it which wouldn't have any effect on the capillary action theory.(Go figure! ) If I were there I would replace the AAV just to check. ( I still keep coming back to a vent problem) This is a very interesting complaint with some very fascinating solutions offered. The only problem is that none of them completely fit the problem. There seem to be a little something wrong with each one. Be fun to find out exactly what's wrong. Regards, Tom

I tried to put a "that's a yes" between less than and greater than signs in my comment, but the forum software removed it.


The most typical scenereo of losing water can be a defective toilet or one with a crack. The crack could be affected by temperature changes, but this should not be that intermittant. It could be affected by temperature changes. But in the house? The top and bottom of the toilet? Just doesn't make sense.

Time to mount a video cam aimed at the toilet bowl? :confused:

Tom:

I thought of one we missed and it would fit the 2 hours after the flush observation. If the OP has pets like a dog, he/she could be using the toilet for a water bowl. I have seen this happen. Water just ater a flush could be considered freher water than in the dish. Dog could be thirstier or more agitated during storms.

Just like the complaint of excessive water use and hearing the toilet flush in the middle of the night we have to think harder. The video showed that the pet cat was flushing the toilet multiple times and playing in the moving water.

Solution in this case is a locked bathtroom or keep the lid down.

Ok Crazy! Do you have a thirsty dog? Bark once for yes and twice for no.
Cheers, Tom

In west Texas we have lots of wind, and during a big wind of say 40 miles an hour I have seen the water in a commode rise and fall as much as two inches, but never enough to break the trap.

Here is my suggestion as to what might be happening. As you all know some commodes flush easier with less water than others, so maybe this is one of those. Add the possibility that the roof vent is placed in a spot on the roof that causes a down draft during a heavy gust of wind or even could cause a lowering of air pressure in the vent thus affecting the water in the trap.

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Originally Posted by letmetellu

In west Texas we have lots of wind, and during a big wind of say 40 miles an hour I have seen the water in a commode rise and fall as much as two inches, but never enough to break the trap.

Here is my suggestion as to what might be happening. As you all know some commodes flush easier with less water than others, so maybe this is one of those. Add in the possibility that the roof vent is placed in a spot on the roof that causes a down draft during a heavy gust of wind or even could cause a lowering of air pressure in the vent thus affecting the water in the trap.

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I was thinking pretty much along the vent line myself. But the toilet in question never had a vent until the plumber installed a AAV. Now I'm questioning the new AAV. This is a weird problem and that's what makes it so much fun. Regards, Tom

Psst. The plumber didn't install an AAV, just a new vent pipe. I suggested an AAV.