clogged drain suddenly drains on its own

[trw888]

I'm a plumbing novice so maybe this isn't uncommon, but it was weird to us and would like to find out what may have happened. Our main line backed up into our shower after my wife flushed the toilet. She was mortified and used a plunger for a good 20 minutes to clear the shower drain, but not surprisingly the plunger had no effect. Than we tried a bladder and garden hose, but it didn’t help either. She then gave up and started searching for another solution. (Like I said, she was mortified and didn’t want to call a plumber just yet. Based on previous experiences, I was ready to call a plumber as soon as it happened). After roughly 20 minutes of just sitting there without us doing anything, the drain suddenly cleared on its own and drained quickly. Things now drain better than in ever in the 5 years we’ve lived in the house. For example, whenever the dishwasher would drain, there was always some backup into the kitchen sink, but now that's gone.

So, my questions: What the heck happened? Is this common? Normal? An indication of anything?

Some background that may or may not be relevant: The house was built in 1952. It’s on a slab. The main line backed up in 12/29 and 4/11. Each time a plumber cleared the line and things were better. The dishwasher still backed up in the kitchen sink, but it was much improved. But each time, the things slowly got worse. Four years ago, we had to replace the p-trap in the shower.

Thanks in advance.

[Gary Swart]

The only effective treatment of a clogged sewer line is a professional plumber with professional equipment. Plunging may clear a clogged toilet, but not the sewer line. Chemicals are not effective either. I will venture a guess that there is something in the line that is catching debris that forms a clog. When drain suddenly cleared, it was because this clog broke loose at least enough to allow the drainage. It may take a camera inspection to find the real cause. The cure will depend on the results of the inspection.

[trw888]

Thanks Gary. I've thought for a long time that a camera inspection would be a good idea, but I keep putting it off. I'm still curious to know if a clog clearing itself and all the drains then working better than ever afterwards is a common thing.

[hj]

It is not unusual. IF it was due to a "soft plug", sitting with water pressure against it could have caused it to eventually clear itself. Whether it was really better afterwards depends on WHAT was causing it and how long it had been in the line. A camera inspection might just show a clean line and so it would be a waste of money.

[trw888]

Thanks hj!