this applies to any antenna, or piece of metal, projecting into the air above your house. There are two kinds of damage lightning can cause....the direct strike and "induced currents and voltage". Truthfully, there is not alot you can do other than try to mitigate a direct strike...the energies involved are just too great. Proper grounding of your electrical system and grounding for all antennas is the only way to prevent (by draining the static electricity charge that appears to attract lightning), or lessen the effects of a direct strike.
"Induced currents and voltage" happen when a lightning strike is near-by. As the lightning passes by the metal in your house, it "induces the flow of electricity" in the metal and wiring and proper grounding can usually take care of this.
So, if you put up a TV or FM antenna, follow the instructions for running a copper or aluminum (I prefer copper) ground wire from the antenna down to a driven 8' ground rod, avoiding any harsh or 90 degree bends in the wire. Also attach a coaxial grounding block to the ground rod and connect your coax feedline to it before it enters the house. AND, run a bonding wire from your new ground rod (or rods) to the main house electrical ground rod and bond them together (required by NEC - the National Electrical Code) to prevent "ground loop hum" in your a/v equipment.
Please, do not consider a copper cold water pipe as a proper "earth ground". In the good ol'days when all house pipeing was copper or galvanized steel, you could assume it would act as a ground. Today there is far too high a chance there is plastic pipe in the supply run to the house, or at places in the house, to make that assumption any more.
Now....that was a long winded answer to a modest question.
