FOLLOWUP! In July 2012- I had sewer gas leaking into my bedroom, bathroom, and then up to the upstairs level of the house for five months. It was awful. I have an 18 inch crawlspace and a raised floor. Under the house is dirt and the pipes. I had FOUR plumbers and TWO handymen check it out. They found NOTHING! They were too big to fit around the pipes!!! We had put in a new toilet, and I had that pulled up and put down again, just in case. but that was fine. We checked all the traps, and now keep them full of water, so they are fine. The plumbers gave me estimates of $4500 for a sewer cleanout installation in front of the house, and $6800 to repipe the bad pipes, if they found any.... I did not have the money, and they really had no plan, just guesses. Last August 2012, I luckily found a neighbor friend who was able to crawl around under the house. He was a little guy, and knew how to do plumbing and other repairs!! He found leaking and large cracks in the main drain sewer pipe at the ground level, around the back of the pipe, hidden from general view and he used epoxy to repair it. This pipe was attached to other pipes, and if it needs to be replaced it will be a difficult job. That pipe was directly below the downstairs bathroom. That reduced about 70 % of the smell and seems to be holding tight with no more leaking there. But sewer gases were still leaking from somewhere else, but not as bad, or as often. it still kept coming back about every three days.They centered in my bedroom, and seemed to come out of the floor. Oddly, from the beginning, the gases only happened around 1am until 5am, then stopped all day long, so no one could smell them, unless they stayed all night. From the first repair, the gasses only occurred about every three days or so, and not as severe, but still stinky. My friend came back into town in November, and went back under the house, and found stress marks on the larger pipe that attached to the MAIN drain sewer pipe, and ran towards the front of the house. This pipe traveled directly under my BED, and the cracks were basically under my pillow area. (What LUCK!) He had to replace that whole pipe, and to get it inside we opened the ground vents and slid it through, and the old pipe out. After he replaced that and all the fittings, the gases were gone! THANK YOU GOD!!! It cost me $800 just to investigate all this, and get nothing for the repairing of it from that! Plumbers were just ready to get paid, with no idea what was actually wrong!!! My friend only charged me $550 plus parts for this! I suffered through it for five months, and hope the sewer gases didn't harm me in any way! I sure appreciate the clean smell now!!! By the way, it was an acrid stinky burning smell. It did NOT smell like METHANE, or anything described as general sewage smells. It was just hard to breathe it, and would cause eyes, throat and nose to burn. I had a runny nose right up to the day the last pipe was replaced, and it all stopped. GOOD LUCK TO ANYONE STILL HAVING THIS PROBLEM. I learned far more about plumbing than I ever thought I would need to know!

I don't see how any toilet - save one on a boat or R/V - could possibly function without a vent stack. "but the vent goes to the garage" would not be approved by any building inspector anywhere in this country. Perhaps it was a "SPOT" - stupid previous owner trick. There is one possibility - other than installing a toilet and vent properly - which apparently was not done. The vent or soil pipe could have been pierced by a drill, nail or screw, especially if PVC was used. As an appraiser. I've seen that happen before. And yes, I *almost* made that rookie mistake myself, installing a new cabinet over the toilet. Since this is a 1938 house with plaster on lath walls, I was using a stud finder and drilling pilot holes. One was in an unexpected location, but it was *perfectly* placed. But it wouldn't drill...and that's when I realized it was the cast iron vent stack. No harm done....

There is a possibility that your "p" trap has rusted through and no longer holding water to block the sewer gas from coming in. Pour some water down the drain and take a flash light and look down the drain and see if you see trapped water down where the "p" trap would make its turn, then in case its a slow leak check it again a few times, especially of the smell comes back.

Obviously this is an older home that most likely did not originally have indoor plumbing, therefore they ran the vent stack up the exterior of the structure. Most codes no longer permit any vents or waste stacks to run on the exterior of the structure, however in this case it would be grandfathered in. Having said that, even though the vent may be permitted to run on the exterior of the building it still must meet the code restrictions concerning how and where it may be terminated. No vent may be terminated closer than 12" from any vertical surface. In urban areas where structures are built close together or where a structure is physically located close to the property line it must be noted that NO VENT may be terminated closer than 10' horizontal from the property line. All vents must terminate 7' above any flat roof that is used as a deck within 10' horizontal from the vent stack. Under the Uniform Plumbing Code (UPC) ALL VENTS must be terminated a minimum of 6" or average snowfall plus 6" above the roof line, no exceptions. Under the International Residential Code (IRC) or the International Plumbing Code (IPC) all structures are required to have one "Main Vent" which must terminate through the roof and extend 6" above the roof line (average snowfall plus 6" in areas subject to frost). Main vents may not have a horizontal offset. (In plumbing any pipe which rises at an angle of less than 45deg above flat horizontal is said to be a horizontal pipe, whereas any pipe which rises at an angle of 45degrees or greater is said to be a vertical pipe.) Keep in mind that the stack in question is a "Main Vent". You could use a pair of 1/6th bends "sanitary 60deg elbows" or a pair of 1/8 bends "sanitary 45deg elbows" and offset the pipe from the wall to the edge of the roof at a 45 or 60deg rise, then extend it above the roof line. Under the IRC when additional auxiliary vents are required they may be terminated through the roof, in the attic space, or through the wall under some rather strict rules. Through the wall vents: a. may not terminate under a vented soffit. b. Must terminate 2' above any opening into the structure within 10' horizontal. c. must terminate 4' below any opening window within 10' horizontal. d. sidewall vents must be fitted with screens to prevent birds from nesting in the pipe. many local codes simply prohibit sidewall venting completely. As a personal note: While the IRC does permit terminating a vent in the attic space I personally refuse to do so and I would highly caution anyone to reconsider before doing so. One of the biggest problems with terminating a vent in the attic space is water vapor from the bath, shower or laundry discharge will eventually be carried into the attic space where it condenses with the cooler air and settles into your insulation. This not only renders the insulation ineffective, it also provides a perfect medium for mold growth. In addition, any heavier than air sewer gases that were carried into the attic space will eventually migrate through the ceiling materials and you end up with sewer stink throughout the house. As if that were not problematic enough, most homeowners and sadly many insulation installers are unaware that DWV vents may be terminated in the attic therefore they inadvertently cover the vents when installing additional insulation. In order to understand venting we must understand the nature of sewer gas. Sewer gas is a combination of a number of gases that are produced by the decomposition of organic materials. If the drain lines are pitched correctly there should not be any major accumulation of organic materials standing in the pipe, however the pipe walls are unavoidably coated with a residue of organic waste material so a minor amount of decomposition is taking place in the pipes constantly. Sewer gas is primarily composed of methane, nitrogen, carbon dioxide, sulfur dioxide, hydrogen sulfide, nitrous oxide and a lessor amount of water vapor. Some of these gases are heavier than air, while others are lighter than air and the proportions of the gases will vary constantly therefore we can never be sure if the gas is naturally rising up the stack or settling down to the main drain line. As liquid flows through the pipe it displaces the volume of the gases, therefore under some circumstances the displaced gas may rise and go out the stack or it may be pushed further down the pipe. The only thing that is certain is that it does move. In addition, as we discharge warm water such as from a shower, tub or laundry discharge the air and gases in the line are also heated and under these circumstances even gases that are basically heavier than air can and will be carried to the top of the stack by the warm air and gases. Once they leave the stack if the outdoor air is still the heavier than air gases will immediately begin to settle towards the ground ergo we smell sewer gases when outside on a cold still day. I would be interested to hear the theory as to why a 180deg bend on the top of the vent stack would prevent the stink from coming out, but let me suffice it to say that it will not work. If you don't believe it, take your shop vac and suck the water out of a toilet bowl, then close the bathroom door for a couple hours and come back and see what that bathroom smells like.