Over 500 people in South Africa have fallen ill from a gastrointestinal illness causing stomach cramps and diarrhoea, which authorities are blaming on poor water quality in two different cities, the Associated Press reported from Johannesburg.

Authorities this week warned communities east of the capital, Pretoria, to stop drinking tap water after 408 people, including children, fell ill and were treated at health facilities. Most of those who fell ill were children under four, according to health and city officials, who said people drank contaminated water from a treatment plant supplying several communities east of Pretoria.

Source: Associated Press via EuropeSays

Officials confirmed the water at the Bronkhorstspruit plant had not been chlorinated for about three weeks, rendering it unsafe, and said the municipality had trouble obtaining chlorine from its usual supplier. The plant draws water from the Bronkhorstspruit River, which officials said is badly contaminated with sewage pollution from poorly functioning wastewater plants upstream. An initial investigation found officials failed to inform residents about the poor water quality.

South Africa's water and sanitation minister Pemmy Majodina told a media briefing that investigations linked the illness to contaminated water from the Bronkhorstspruit works and found the plant operated without chlorination between September 24 and October 14, the Sowetan reported. Tshwane mayor Nasiphi Moya said the investigation found city officials had failed to warn affected areas that the water 'had not been chlorinated and therefore should not be drunk or used for cooking, washing or bathing, even after boiling.'

Source: The Sowetan

On Wednesday, city officials distributed water through emergency tankers while the charity Gift of the Givers supplied bottled water. Various political parties have called for Mayor Moya to resign and for other officials to be fired over the contamination.

Separately, in the coastal city of Gqeberha in Eastern Cape province, at least 111 students from Rhodes University have been treated for a gastrointestinal illness over the last few days, the university said on Wednesday. University and water authorities were investigating the cause, but also suspected water quality, spokesperson Olwetu Gwanya said, urging staff and students to drink boiled and cooled or bottled water and to practise safe food handling and hygiene. No deaths were reported in the Bronkhorstspruit cases in the local investigation reporting.