The Ministry for Primary Industries is warning travellers from Fiji to stop bringing so-called miracle water into New Zealand.
Border staff have seized the water from nearly 500 air passengers since November.
Sourced from a natural spring on Viti Levu, the untreated water is claimed to have healing properties that can cure conditions including conjunctivitis and blindness.
Travellers face a $400 fine or $60 treatment cost if they have the water, which can carry diseases harmful to freshwater aquaculture and environment.
The ministry is currently running an awareness campaign, including notices at Nadi Airport.