I have a pH meter on my water inlet and the reading jumps all over the place. The manufacturer says the water needs to be grounded. Do they make something I can insert into a 2" PVC pipe and hook an earth ground to it?

How is your house grounded? You can't ground PVC.

The manufacturer says the water needs to be grounded.
Did manufacture say water needs to be grounded or did he say meter needs to be grounded?