I have small amounts of water seeping from the base of the toilet around the wax seal. Plumbers have taken up and re-sealed several times once even using plaster of paris to level out the floor. Each time after a few days we see water again. We had plumbers snake out the line, even sent a camera down. They told me that the old drains under the house were cast iron, and that there is a spot that the cast iron meets pvc that they can't get the camera through. They aren't positive they say, but they are telling me that they think the water seepage is caused by a partial obstruction down the line somewhere. Let me say that the toilet flushes fine, doesn't back up, all the plumbing drains the way its supposed to. We even snaked out the vent from the roof to the toilet and they told me there was no obstruction there. My question is... is it possible that some partial obstruction down the line will cause water to back up and come out at the seal even if the line is clear some 80 feet to the obstruction? I ask because they are advising me to break up the concrete on my patio to look for the problem in the drain. HELP!