"Dan Harms" wrote in message
m...

I haven't done that, but I did the opposite - pouring water directly
into the drain, and it does NOT increase the leak. My best assesment
is that the source of the leak is just old caulking/grout on the
shower floor. Looking at the Home Depot books, it looks like
regrouting is something I could do myself over a weekend. Could it
really be this simple?

It could be that simple. Or, it could be a leak in the caulking/putty
around the drain. Or, it could be a leak from higher up that is just
finding its way to that low point where you see it coming out. If you can
re-create the leak by starting low (filling the basin first, putting water
on the floor outside the shower, etc), then you know the leak isn't coming
from higher up in the plumbing, fixtures, walls, etc.


BTW - what's supposed to be underneath the tile on the floor of the
stall of a typical 1960's built house in DC suburbs?

I don't know the answer to that one but I'm sure someone else here does.