I live in gulfcoast Florida and have been plagued by persistent (1-2
per year) pinhole leaks in the copper pipes in our home (1990). One
interesting aspect is that, so far, all the pinhole leaks have occurred
in cold-water lines. I am not sure what that may indicate, but,
perhaps, someone has an opinion.

I have read many of the posts concerning the many theories for the
causes of this problem, i.e., acicidity, electrical currents,
chemicals, minerals, etc. Regarding possible electrolysis and stray
electrical currents, I installed a new grounding rod on the main
electrical box outside the house (right near where the water line
enters, incidently). However, I noticed that my second-floor electric
water heater is grounded to the copper piping adjacent to the heater.
Having read a lot of posts commenting on the need to isolate electrical
currents from the water system, why would a water heater be grounded to
the water pipes? Does this make sense? Should it be changed?

Any suggestions for diagnosing and/or addressing this pinhole problem
would be appreciated.