I live in a one story house on a concrete foundation. I believe our main drainpipe is clogged. After flushing our toilet about 5 ot 6 times, the water backs up. It does drain out, but very very slow. I tried a 20 ft auger in the toilet, but I dont think it reached the clog. And now I cant find a cleanout plug. Do all houses have a cleanout plug? Are they placed in a standard location. I noticed a letter S on the curb in front of our house. Is this where the drain pipe runs into the sewer? Would a chemical unclogger work on this kind of clog? I would greatly appreciate any help.Daniel Hammond