Many pool owners do not understand the difference between grounding equipment versus bonding pool water.
Grounding Equipment: Electrical wiring system which is a conductor that provides a low impedance path to the earth to prevent hazardous voltages from appearing on equipment. All your pool equipment should be grounded for safety.
Bonding Pool Water: Bonding ensures the safety of all pool swimmers by making sure there is no build up of electricity in the swimming pool water. No current flow can take place between two bonded bodies because they have the same potential. Bonding keeps people and electricity separated.
Bonding protects people and equipment by reducing current flow between pieces of equipment (or water, or swimmers) at different potentials. The main reason for bonding swimming pool water is personnel safety. Bonding prevents someone touching two pieces of equipment (including water) at the same time from receiving a shock (or worse) by becoming the path of equalization if they happen to be at different potentials
2008 the National Electrical Code (NEC) has mandated that pool water shall be electrically bonded, not just metals in the structure of the pool itself. NEC bonding requirements apply to in ground and above ground pools, and includes all metal components, equipment and the water itself. Correct pool bonding protects people, pets and pool equipment by reducing current flow between items of different potential.
All pool water should be bonded. Your pool water must be bonded when you do not have any metal touching the water (ladder, hand rail, metal fixture or light). If you do not have bonded water, or you are unsure, a simple pool water bonding kit will do the trick. Just make sure your bonding kit is stainless steel (do not use copper or other metals) like this one: Burndy Waterbug Pool Water Bonding Kit .
Here is a great article on swimming pool water bonding: