Weird toilet

[pete]

We recently built a house for my brother and we have a weird situation that we can not figure out. The basement bathroom toilet is plumbed with Cast Iron set in the concrete floor. For some reason after the toilet is flushed and left alone for about 3-4 hours it goes dry, no water in the bowl. It does not go dry right away. Why is this happening? Does not happen in any other bathroom in the house or anywhere else in the development? Could the pipe be "overpitched" causing the water to drain out? We have closed the lid to make sure it was not evaporating (we thought that was unlikely)...

Truely baffled,

Pete

[Norm]

If this toilet is the last and lowest fixture in the house the rush of waste water from higher fixtures discharging could siphon the water from the integral trap in the toilet and drain the bowl. Does this occur when no other waste water is discharged?

NORM SAGE

[Richard Moore]

Pete...as Norm said...which might be exacerbated by a problem in the venting system.

[pete]

It is the lowest fixture in the house and the farthest from the trap. We will have to try an experiment and see what happens. I will tell him to use that fixture last tonight and then check it in the am. If it does not happen then it sounds like Norm has figured it out.

Richard--what kind of venting problem? Oversized, is that even possible?

Thanks for the answers, I knew someone here would have some ideas.

Pete

[Chad Fabry]

My last house was an EXTREMELY tight home and nearly every day at some point barometric pressure would drop rapidly a half point. It literally sucked the water out of the toilets and sink traps. You could forecast rain if there wasn't any water in the toilets. I fixed it by opening a window. I hope my fix wasn't too technical for you folks.

That was then; my current house is more convenient in that one can store cold cuts against any exterior wall all winter long. Vegetables seem to do best on the north wall of the dining room. I call it the "crisper" section.

[hausdok]

Man, don't you guys know anything?

Pete's in New York. New Yorkers are famous for flushing baby elephants down the toilet. They then roam the sewers and look for conveniently low toilets to snake their trunks to for a clean drink of water. []

OT - OF!!!

M.

[Richard Moore]

Pete...I was actually think more along the lines of undersized or even blocked or missing vents. A large "slug" of water from an upstairs toilet then creating enough "vacuum" to suck the lower one dry. Trouble is...I don't know if that makes any sense. [:-crazy]

I guess I'd want to see if the water went down gradually over the 3-4 hours (possible leak in the bowl?) or all at once. Maybe a rubber ducky on a string attached to a contact attached to a buzzer etc etc...?

--- 15 minutes later after some pondering ----

When you say dry do you mean DRY? I can't see any wierd suction doing that. Pulling some water out yes...but not all of it. It sounds like you may have a porous bowl that is leaking the water into the slab on the outside of the flange.

Please pass Karnac the next envelope!

[Norm]

Pete,

Please don't keep us hanging. What is the conclusion to the "dry toilet" situation? This stuff sucks. WHY?

NORM SAGE

[pete]

Ooops sorry --I will check with him. I sent him everybodys thoughts and we thought the explanations sounded reasonable. We are pretty unhappy with the plumber and will be switching for the next project.

Pete

[kurt]

There are very few problems that occur in plumbing systems that aren't leaks or vent inadequacies. Leaking is easy to figure out; vent issues are a little trickier, but not rocket science.

My guess is vents, or lack thereof.

[Howard]

Hey All-- I am the "brother" with a dry toilet. Tonight I came home and checked the toilet (funny as it may be that when I get home I check my toilet before my answering machine) and lo and behold--it was wet. Full!!! Therefore I do believe that Norm hit the nail on the head. Although I do like O'Handley's theory better. Now for the million dollar question---What should I do?

--Howie

[Richard Moore]

Howie or Pete...more questions.

Pete stated that the house was recently built but the toilet in question is plumbed with cast iron. Is this a rebuild on an existing foundation? Was the old cast iron stack vent discarded or otherwise terminated or capped? Could a new main stack or connections have compromised the venting for the problem toilet?

Solutions? Hmmmm. If it's none of the above that can be easily remedied, I would think an air-admittance valve somewhere close to the toilet would be the simplest, but not easy, answer. It would take some nasty slab excavation and plumbing. Failing that you might think about some sort of trap primer (normally used to maintain the seal in basement drains).

[pete]

Richard you seem surprised to find out that a new home builder still uses cast iron for waste lines. I can understand your surprise. Most new home builders in this area are still using cast iron (no hub) for undergrounds and below slab applications and pvc above that. We however continue to use cast iron for all waste lines and pvc for venting only. The cast iron is much more effective at containing the sound of rushing water. However we may be forced to give in to the price pressure for our next project. PVC is the plumbers preference so they really push with their prices.

Pete

[hausdok]

Hi Pete,

Actually, Richard's surprise probably stems from the fact that ABS has been the overall favorite out here for 30+ years. I do occasionally see cast iron in new high-end homes where cost isn't a consideration and you know at those prices folks aren't going to stand for the sound of rushing water. I think I've seen PVC used here about 5 times in 8 years.

ONE TEAM - ONE FIGHT!!!

Mike

[hausdok]

Hi Pete & Howie,

I've been struggling with the impression for several days that I might know what is causing this, besides the elephants, but I couldn't quite put my finger on it. It was back there in the cloudy recesses of my mind, but I just couldn't reach it. Well, it just came to me.

I remember reading an article in PM mag about a year or two ago, that I think was written by Dan Holohan, about trap/drain problems and odors. If I'm remembering this right, he got a callback that was driving him crazy, until he realized that the problem wasn't the plumbing, it was a newer high-capacity washing machine that had an extremely high volume discharge pump that needed a larger drain.

How does that apply here? Well, you said that the toilet was farthest from the trap and I'm guessing you have a basement laundry placed between that toilet and the vent stack. When the washing machine pumps out, it pushes a high volume of water into that pipe for a couple of minutes. Is the trap in the bottom of the toilet then acting like an air admittance vent with the water being siphoned out?

Try this, set the washing machine for 'large', start it and then advance the timer dial to the discharge point and watch what happens in that toilet as the washing machine pumps out.

ONE TEAM - ONE FIGHT!!!

Mike

[Norm]

That might work Mike but to confirm it (if it happens) they will also have to see what happens with the washing machine not in use while flushing the toilets or emptying a tub located on the upper levels of the home. Isn't this like the Venturri effect you get in spas and hydro-massage bathtubs which have adjustable air admittance valves in order to increase or decrease the bubbling effect of the system?

NORM

[Richard Moore]

Great thing about these forums is you keep on learning. Yep, I thought cast iron was pretty much "ancient" history. I now know better.

Maybe we can get Pete or Howie to post a rough diagram of the waste system?

[Brian G]

I thought cast iron went out decades ago. I only find it under older houses here, which always calls for the "limited remaining life" warning. Does anyone know what the rated life for PVC is? I don't think I've ever seen anything on that.

Brian G.

[Howard]

Mike--

The washer is actually closest to the house trap, and the discharge line has its own vent. Also, I have only used the washer 4 or 5 times--I just moved in 1.5 weeks ago. Also, This morning, after using an upstairs toilet a few times and taking a 2nd floor shower, when I came down to the basement, the toilet was still full. And, I have done 2 loads of laundry today and the toilet is still full. Once again--baffled.

As for the no hub vs PVC/ABS debate--a few years ago I was working as a CM for homebuilder in the suburbs of Chicago, and my plumber used PVC waste. There were countless times when the plumber missed a nail plate and the drywaller screwed right through the plate. Thats a pretty sh***y mistake.

--Howie

[hausdok]

Okay then,

Sounds like we're back to the elephants. Sure you don't have a pooch that likes to drink out of the toilet?

OT - OF!!!

M.