Today as I was showering, I heard the toilet gurgling. Sure enough, air bubbles were coming up through the toilet water. A short time later, the bathtub stopped draining. (It's now gone down, but took a long time.) What's going on here? What causes the toilet to blow bubbles? What should I do now?

 

It could be an occluded vent line or clogged main drain line. Are you on municipal sewer or a septic tank?

 

Municipal sewer.
After showering a couple minutes, the toilet gurgles and the tub starts draining very slowly.
With no water in the tub, if I flush the toilet a couple times, I hear the tub p-trap splash and the toilet drains slowly.
Owned this house for 8 years and never had this problem.
This bathroom is downstairs and is the farthest from the main outside cleanout.

 

I agree with Larry, you need to snake both the tub drain and the toilet. I'm betting the clog is at or near the vent opening.

 

Gurgling can also indicate a main sewer pipe is completely full of water, due to severe blockage.

If snaking doesn't work you might need a plumber with a snake and cutting head to clear out the main pipe.
If the problem returns soon after snaking, I would get a camera inspection of the pipe to ensure the pipe has not broken or collapsed.

 

No luck. Here's what I've tried:
1. Snaked toilet with 3-ft toilet auger.
2. Snaked tub with 25-ft auger.
3. Snaked vent from roof with 25-ft auger.
4. I dropped a garden hose down the vent until it stopped. The bottom 10-feet of it was wet when I pulled it out.
5. Snaked cleanout back toward house with 25-ft auger. But, I have no idea how effective this was or which branch the snake took. The snake didn't behave well in the 3" pipe.

In the cleanout, I can observe a slow flow of water when the tub is slowly draining. There's definitely no backup from the city side. When I run the upstairs tub, I observe a good flow of water in the cleanout.

At 25-feet, my snake might not make it to the first branch, which would be the clothes washer. It definitely doesn't reach the vertical stack from the upstairs bath or the cleanout.

Should I go buy a 50-foot snake that would reach from the tub all the way back to the cleanout, or is it time to call a plumber?

 

It's your call on purchasing the snake. My opinion is it's good news the blockage is not towards the street, so a normal snake might fix the problem.
My initial guess was major blockage or cracked pipe in the yard towards street.

 

I think it's worth the cost of the 50 foot snake. At the very worst you have another tool for future use.

 

Good call. I used the 50-foot snake, and things are better but not 100% fixed. I still have gurgling in the toilet, but the tub and toilet drain much faster than before.

I wasn't able to feed the snake from the tub overflow. It just wouldn't get past the p-trap. So I dropped it down the vent from the roof. If I hit something, it wasn't very significant because it took very little effort to feed all 50-feet. I never even had to twist it.

I think I'll try it again from the roof. Is it possible there's something soft that's clogging the pipe that I need to punch through multiple times? What does a pro do differently?

 

You indicated the bottom 10' of your garden hose was wet when you pushed it down the vent. It sounds as if you may have an occlusion either low in the vent or the back up was going past everything and up in the vent. I would try the auger from the roof if you feel safe doing it. There shouldn't be any standing water in the vent.