How can I fix a toilet that is backing up with sink water?

Question

I need help. I would like to avoid calling a plumber. The toilet in our downstairs bathroom keeps backing up.

Here is what I have tried and/or observed:

1. I tried using a good plunger. I cannot even get a little bit of the water to drain with the plunger.
2. I tried using a good toilet auger. I can get the toilet auger all the way through. I did that a couple of times. But no change.
3. When I turn on the faucet to the sink that is next to the toilet, the water gets rerouted back up the toilet.
4. I turned on all of the faucets and the shower and bathtubs upstairs and flushed the other two toilets upstairs. They all are all fine and do not impact the downstairs toilet at all.

I do not have a lot of home improvement experience. I did have to remove a toilet once before to get a toy out. It was a pain in the butt for me to do since it took me like three hours from start to caulking. But I'll try just about anything before calling a plumber.

What advice can you give me to help me fix this myself? Is it even worth removing the toilet given #3 above?

Answer 1

If the sink is backing up into the toilet, then the clog is at or after the junction of the two in your drain lines. You'll have to snake the drain to remove the clog, and it will likely be beyond the reach of a standard toilet auger. You could remove the trap on your sink and attempt to snake it from there, or remove the toilet and run the snake down that drain.

If you do remove the toilet, you should wait for the water in the lines to recede so it doesn't flood your floor. If you go through the sink drain, you'll likely have a smaller drain line to maneuver the snake and it's possible the clog is further away, requiring a longer snake.

Answer 2

Sounds to me like your sink and toilet run to the same sewer line and the clog is after they join.

You won't be able to plunge it free because the water will push back up the drain towards the sink rather than applying pressure on the clog. Even plugging the sink drain won't help because there is a vent stack that will be open (and you don't want to risk plugging that as cleaning them requires going up to the roof).

If there is a large-sized clean-out access that you can open (be prepared for some possibly not-nice stuff to come out when you open it) then get a full-size auger and clean it out from there. If not, you'll have to go through the toilet or remove the toilet. I'd give in at this point and call a professional.

A small-size auger will just dig a small hole through the clog. It will drain but the next solid waste to go down the toilet will likely clog it up again.