Main Equip Bonding question

[The Dentist]

Just recenty had a 5 year PIR done at the place I work at, and it failed on the sprinkler system not been bonded to the MET, althought the sprinkler isnt dirctly attached to the mains water ( its an independantly pressurised system which is supplied by on site tanks topped up by the mains water)

Does this require bonding to the MET??

The water mains for the sprinkler system is about 500 yards from the MET, its a TNS system, so I imagine I have to run a 500 yard earth cable of (???) diameter to this, yet the main water and gas are bonded at source within 5m of the incomer?

Can this be bonded at its neares source, ie the localist sprinkler pipe or do I have to run a cable to the incoming source?

Thanks

 

[Spark123]

Can it introduce earth potential (or another potential) into the equipotential zone? Does the supply for the sprinklers come from the tanks underground via metallic pipework into the building? If so then I'd have thought it should be bonded where it enters the building. If the tanks are in the building I'd question the need to MEB them.
If you have a 100A supply the MEB should be so that it does not exceed approximately 0.05ohms.

P.S. that is one big dental surgery