Jeffry,

Thanks for the response. I too was very skeptical of the overflow tube
not catching the water. I have been told that some plumbers will
increase the water flow into the tank to make it fill up quickly, but
when they do that, it exceeds the capacity of the overflow tube. Of
course, your two causes might be to blame as well. An engineering firm
now has our toilet and is preparing a report for the insurance company.
I will say that the exact same thing happened down the street to a
family which had the same builder and the same plumber as a
subcontractor. I am hopeful that something might come out of
subrogation.

Collins