Friend of mine as a fairly large pond circa 2,000 gal. From an electrical point of view it has a double insulated submersible pump and a UV light that is housed in a plastic enclosure that the water is pumped through on its way to the filter before returning to the pond.
These are supplied on a separate RCBO circuit from his CU. A 2.5mm SWA twin cable runs from the CU to a junction box ajacent to the pond and whilst not used the earth (via the SWA) is available for connection. The house is supplied from a PME overhead supply.
He asked me if I thought the water should be earthed (the pond is lined with a PVC liner so insulted from earth) and if so should he dangle a length of copper wire into the pond with the other end either connected to the SWA earth terminal or drive an earth rod into the ground and connect it to that.
opinions most welcome.
thanks Andy .