Septic system backed up rather suddenly and after having the tank opened and pumped the tank outlet pipe that keeps floating solids from entering the leach field was found in two pieces lying in the bottom. Currently in the process of having the lines jetted to hopefully remove enough of the solids that were carried into the distribution line and installing a new pipe in the outlet.

My question is what would make this pipe fail? The installation is 37 years old, the inlet pipe appears to be in good shape, many homes in this area or as old or older and have not had this kind of problem. We've been adding 'bugs' to the septic for a number of years since the white water from showers, sinks, and laundry all go to the septic tank. Could some types of septic additives cause this?

 

You haven't really told us anything about your outlet "pipe" that failed so it's difficult to comment. There are pre-cast concrete dams built into some tanks while others use a simple T turned vertically on the end of the outlet pipe while more modern septic systems have a plastic filter on the outlet.

 

Did the pipe break into two pieces or did two pieces come apart? I doubt any additives like yeast or RidX would cause any harm to the plumbing. I wouldn't be overly concerned about the cause as it's not likely to happen again.

 

My 1987 concrete Septic Tank had a concrete baffle at the outlet which began crumbling after a mere 10 years.

It was explained to me that the concrete was poured into the form late in the season that year and had probably froze and not cured properly, so I introduced a plastic filter (Zabel) which now also serves as a baffle.

 

After retrieving the pieces from the bottom I was a bit surprised to find the pipe was some kind of cast metal that did in fact break apart and fall out. I asked the man fixing it for me and he said it's probably the methane gas but didn't know for sure. He also said he's only seen it with the outlet pipes? He replaced it with what looked like PVC.

 

Sounds like a cast iron pipe. PVC has a good track record so there shouldn't a re occurrence.

 

Don't know where you are located, and possible that you're on the right track, needs to be addressed regardless, but could also be two unrelated issues. Anyway, the point is, do you have snow on the roof, and is it possibly covering the vent stack(s)?