Many of the country's most popular swimming spots are not safe, according to a water quality survey by Consumer New Zealand.
The survey, of 500 popular swimming spots, found 29 percent of beaches, lakes and rivers had bacteria levels so high that the Ministry for the Environment recommended staying out of the water.
Consumer NZ chief Sue Chetwin told the New Zealand Herald a lack of helpful information from councils meant swimmers at many other beaches may be at risk of campylobacter and ear, eye and skin infections.
During summer, councils test enterococci and e.coli levels at popular swimming sites weekly.
About half compile the results over several years to rank beaches in five grades, from very good to very poor. The likelihood of contamination from sources such as stormwater, sewage or agricultural run-off was also taken into account.
Good and very good beaches are safe for swimming most or all of the time, while poor and very poor beaches are not safe for swimming.
Consumer NZ compiled results from 10 regional councils and found only 17 percent of 501 graded swimming spots ranked "very good", 29 percent were "good", a quarter "fair", and the rest -- 29 percent -- ranked poor or very poor.
Ocean Beach stream in Northland and Kawakawa Bay, south of Auckland, were among those ranked very poor, and among those ranked poor were spots at Paihia, Mangawhai, Gisborne's Waikanae Beach and Rere Rock Slide.
