New Diesel's in NZ - The case of the failing engines

New diesel engine require very pure fuel. The water content must be very low.
Much of our local Diesel supply is not up to standard.
When the engine's fail who is at fault?
The supplier of the fuel for not meeting the appropriate standard?
The importer of the vehicle for not ensuring that their product will survive on the local market?

Unless the fuel suppliers are stating that their fuel meets some standard of purity related to water content it seems like it would be difficult to put the blame on the fuel suppliers. Given that earlier diesel engine's did not suffer the same problems such a claim seems unlikely.