Liquid Plumber poses a serious hazard to anyone working on the system.

Not good.

So what happens when it all (most) drains through? That is the stop isn't complete, the water does slowly pass through to the septic tank, taking the cleaner along with it.

What is the danger, caustic? If it is so powerful why would it not resolve most blockage? It is now several hours later and I tried to pass some water through the system. I took several gallons to fill the pipes again, which happened, i.e., the cleaner did not remove the block, it just seeped by it.

My low point is a toilet on the first floor. While running water into the drain via a laundry sink I stopped when I could again see the water rising in the toilet. The surprise is when there water backs up into the toilet, the joint starts leaking. Stopping the water flow into the drain before the toilet overflowed, didn't stop water from entering the basement at the lower PVC joint to the toilet. Seems when the pipes are flowing the water and waste just passes by that join without any leaks. Thank god.

The wax seal of toilet to drain line is not really designed for any significant water pressure or standing water.

It is more of a seal for water that quickly drains away, and gas from the sewer line.

Thanks, that's my conclusion.

I have pulled the septic cover and the baffle doesn't seem to be the problem. I tried to get the bronze(?) clean out cap off of the 4" cast iron line going to the septic tank, but couldn't budge it.. in fact I put so much pressure on it it sprang a small leak, still some water behind the clog.

I called for emergency service from Rooter Man, not to be confused with Roto Rooter, a trade mark. He said he'd be here by 5 pm and is prepared to replace the clean out cap, I think he'll have to take a chisel (or what ever an expert uses) and break the clean out cap to get it out of the drain line.

If I could have gotten the cap off I could have cleared the clog myself... If I was home alone (wife not visiting anywhere at this time) I would have tried some more, I can always use a neighbors toilet when that becomes necessary.

For your original post, use a 4' piece of pipe on the pipe wrench and turn the cap off. You should have a replacement ready.

"I think he'll have to take a chisel (or what ever an expert uses)"

Not that uncommon at all.

Years and years of corrosion have probably joined that plug to the CI pretty permanently.

Break up the old one carefully so that you do not create any leaks in any lead-oakum joints or crack the cast iron.

Use a new plastic plug and compatible joint compound.

Thanks, I did hire the job done. As I had the septic open he rotary cleaned form the septic end, which had a clog I misjudged. I took a garden hose and poked in the baffle/box and felt a solid bottom, thinking it was part of the concrete box. He said no and hit inside the box real hard with a pole and broke through. He did a little scraping with a pole scraper and asked me to run some water. Nothing much came through, so he took his rotary cleaner tool and ran it up toward the house from the septic end. That broke loose more "grease" and water began to flow.

We then went inside as I had damaged the clean out plug and it was leaking through the center "Nut" area. He took a chisel and hammer and began to give it a real whacking, far more heavy hitting that I was prepared to do without specific experience, which I now have. He broke out the center and then collapsed the edge in.. then removed another couple of cups of grease and put on a new cap, using Teflon tape on the threads.

Overall I see most, except the rotary cleaning, I could have done myself, oh yes, and knowing better how the box/baffle is constructed in the septic tank.

I was surprised to see such a build up in the cast iron pipe, and I suppose even PVC does the same.

Relative to using "Liquid Plumber" or whatever, the service guy noticed the smell of bleach/cleaner and commented. I confessed on what I had used and asked if that was a concern to him, he said he had no concerns. My concern, it didn't work or maybe even help.. a little help was no better than no help.

I was pleased with the service and the charges seemed to be reasonable to me, and were flat rate, there was no clock watching. He was also willing to give me a little "class room" time so that I could do more myself.

Undigested grease is not good for septic systems nor for keeping drain pipes flowing well.

Here is a link that might be useful: Click here

Thanks, I got (am) a little confused by the term "grease".. should I take that to be whatever concoction results that bacteria has not been able (yet, or ever) to break down? Then if broken down would be what? Just liquid?

"Thanks, I got (am) a little confused by the term "grease".."

Fat and oil from food and cooking.

Restaurants use a special grease trap to prevent it form going down the drain (though the grease trap needs to be cleaned and it is a messy smelly job).

If the fat is solid and washed down with cold water it might make it out of your lines.

The problem is that if the line is warm from hot water the solid grease can still melt and stick.