I bought a home with an in law apt that has its own septic in the back of the house. The rest of the house has the plumbing and septic in the front. There is no stink pipe. I don't know how they did it without a stack. Is my only option now is to go through floors and ceilings from the basement and through the roof? Not sure where the smell is coming from. I know its not the kitchen sink. The bathroom is very small and the smell is not overpowering but certainly there. I've stuck my nose against the shower drain and hand sink drain but cant really detect the odor. I will be removing all the floors and walls as I remodel and will have a better idea of how all this is plumbed. Right now it looks like the kitchen sink and bathroom sink drain into the line running from the shower and into the main drain from the toilet and then straight outside to the septic system. Im amazed it is working at all. I'm just trying to figure out how much to budget to fix it. Hoping that I don't have to go inside the house against the outside wall all the way to the roof. The upstairs has already been remodeled
Plumbing – Toilet venting, no stack installed
plumbingventing
Related Solutions
Sounds like the main drain for the bathroom may be restricted.
As you shower the water doesn't drain away fast enough, and the plumbing begins to fill with water. As the pipes fill, air may be forced out through the toilet trap causing "bubbles". Since the tub is the lowest drain, the water backs up there first. If you continued to shower, you'd eventually see the toilet overflow as well (if the tub edge is higher than the toilet rim). If the tub was deep enough, you'd eventually see the sink overflow too.
If you look at this crude representation of your bathroom, you'll be able to see what I mean.
Now, if we add in a clog we can start to see what happens when you shower.
As you shower the water cannot pass through the clog fast enough, and the pipes begin to fill.
At this point, any air trapped in the line between the drain and the toilet trap will be forced out and bubble up trough the trap.
As you continue to shower, the tub is the first to back up.
Eventually, if you shower long enough the toilet could also overflow.
Depending on the height of the sink, quite a bit of the bathroom would have to fill before it overflowed.
The first thing I'd try is to clear the drain using a Plumber's snake. A hand auger would likely work, and can be purchased at a local hardware store fairly cheaply. Drill powered augers are also available for a bit higher price, but require a bit more of a gentle touch (and obviously a drill).
Another option is that the vent for the bathroom is clogged, or not sized appropriately. If vent stacks are not covered properly, leaves and other debris can become lodged in the pipe and prevent air flow. A clogged vent will cause the fixtures it's venting to drain slowly, and the results can be similar to a clog as described above.
As with the clog, the solution to clear the blocked vent is a Plumber's snake.
The primary concern with any opening is bulk water infiltration. Sound practice is a minimum of 8" between the sill of the opening and the roof surface to provide for proper flashing and counterflashing. 12" is better.
So long as the duct layout and clearances are consistent with the manufacturer's recommendations, the installation should otherwise be fine.
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Best Answer
I suspect you have an air admittance valve. Based on your description perhaps it is under the sink or even (improperly) in the wall.
An air admittance valve is commonly used for venting things like islands where alternatives are complex and there is no stack. They often leak sewer gas, though, and are often prohibited for use.
On the bright side if you're going to replumb anyway you should be able to add a more reliable vent fairly easily (though perhaps a little tedious)