More than 50 people at Tangalooma Island Resort on Moreton Island, off the south-east Queensland coast, have fallen ill with gastroenteritis.

A Queensland Health investigation has found the resort's drinking water supply has become contaminated with E. coli bacteria.

The water supply at Tangalooma Resort has become contaminated with bacteria, according to Queensland Health. Credit:Mark Higgins

Further testing will be carried out, but in the meantime, guests and staff at the resort should boil their drinking water or buy bottled water.

Metro South Health public health physician Dr Kari Jarvinen said people at the resort or who visited recently needed to be alert for symptoms of gastroenteritis and seek medical advice if necessary.