A number of teenagers have fallen ill after a skate park was transformed into a makeshift pool filled with river water.
Pictures show at least 20 young people swimming in the dirty, brown water during the recent heatwave.
But the decision backfired when several have since fallen ill and are believed to be suffering from sickness and diarrhea.
In New Zealand, Taranaki has seen at least 24 cases of cryptosporidium since the start of year compared with none for the same period last year.
Dr Jonathan Jarman said, “Some of the cases were children but half were adults, and similar outbreaks have also been seen in other parts of New Zealand … some cases in Taranaki became unwell after recently swimming in a pool.”