TOPIC: false reading on a ground

If the main ground wire is connect to Worsbo (don't know how to spell it but that plastic water pipe) is there any chance that an electric tester that you plug into an outlet would read that the outlet is grounded?  I'm guessing that it will always read open ground but just want to double check.

If it's connected to a plastic pipe I can't see how it would read anything but an open ground. It has to be connected to metal to show that it's grounded.

Just a thought here: The tester only uses a wee bit of power to do its job.  I wonder if a bit of condensation on the waterline would be enough for the tester to show that it is grounded.
Why in the world would anyone connect a ground to a plastic line is beyond me.  It is one thing to have it connected to a metal line that changes to plastic, but connecting it to plastic?

Who knows why people do any number of things...it's job security for us!!!!