Hi.. thanks for any help. I have a full bathroom in the garage, and a
full bathroom upstairs. Whenever someone takes a shower at either the
upstairs or downstairs shower, water leaks from the base of the
downstairs toilet. thanks again!! Some things I found out or tried:

1. it is definately coming from the base of the toilet, i have watched
it slowly seep out. and the back and side of the bowl and tank are
dry.

2. when using the upstairs shower, water will leak from the base of
the toilet AND the downstairs tub has water backed up into it.

3. the leak only appears when someone is taking a long shower. the
leak will appear approximately 7 minutes into a shower, then water
will start to steadily seep out from the base of the toilet. i come
back 1 hour later and flush the toilet while running the water in the
downstairs shower, but the leak doesn't appear. i come back another
hour later and flush the toilet 4 consecutive times, still no leak.
so the only time there is a leak is during long showers.

4. pouring draino into the downstairs shower does nothing!

steve