A hoax warning of poisonous water in the Waikato river is one of many pranks that keep cropping up, with social media often fuelling the confusion.
The Waikato Regional Council has reassured locals today that a chemical spill warning doing the rounds on social media was a hoax.
The warning said hundreds of thousands of litres of dihydrogen monoxide is spilling into the Waikato River, and if breathed into the lungs can be fatal. Technically speaking, the hoax is correct, as dihydrogen monoxide is water.
The council said the hoax had been around since the 1980's but appeared to have resurfaced again recently.
They said it created real worry, fear and concern for some people.
In 2007, National MP Jacqui Dean was caught out by the hoax, and sent a letter to Associate Health Minister Jim Anderton, asking if the Expert Advisory Committee on Drugs had a view on banning the chemical. And in 2001 a staffer in Green MP Sue Kedgley's office said the MP would be "absolutely supportive of the campaign to ban this toxic substance" if she had enough time, which she did not.
The recurring hoax was one of many pranks that continue to crop up time after time.
Last year many Facebook users were duped into believing they would receive a share of chief executive Mark Zuckerberg's fortune if they reposted a status.
The status promised 1000 people would be selected to receive $4.5 million each - and was widely shared by those hoping to get in on the action.
It was, however, revealed to be a hoax.
Drivers are often among those targeted by pranksters. An urban myth, believed to have originated in America, involves warning drivers not to flash their headlights at oncoming cars as they could become the victim of gang initiation.
The New Zealand police website warns of a range of hoaxes and urban myths that regularly make the rounds.
They include queries around dialling 112 from a mobile phone for certain emergencies and entering a PIN backwards into an ATM to alert police if you were in trouble.
The Department of Internal Affairs website also warns against a number of scams, with formats ranging from email, text, online, phone, postal and fax scams.