Ruben Undheim wrote:
"Should I use the water pipe system as a ground, or should I use a thick
wire dowen to a ground rod?"

A 20M dipole needs no RF ground. It may get a lightning surge in search
of ground, a path to the earth.

To dissipate the surge to earth it is advantageous to use the same path
as the radio power supply takes to earth, not to create a big potential
difference within the radio.

As the power service to the radio may have a high RF impedance, which
would also oppose a surge, it is a good idea to also connect the thick
wire down to a ground rod.

Arc-gaps between the antenna feeders and the radio case may encourage a
surge to take the direct path to earth. The radio case must also be
connected to the electrical ground and the new ground rod at this point
(perhaps your shack).

All earth grounds must be connected together using approved connectors
to satisfy most electrical codes and to avoid differences of potential
between earth connections. Voltages and currents can be so large that
solder can melt. Welding or specified connectors are required.

If lightning takes the direct route to the earth via the arc-gaps, there
will be less stress on the electrical system.

Best regards, Richard Harrison, KB5WZI