BBC - Residents living near South Africa's capital, Pretoria, have been warned not to drink or cook with tap water after more than 400 people, mostly children under four, fell ill after drinking contaminated water.
The cases were detected in Tshwane, the area which includes Pretoria, after people reported to their local hospital with "stomach cramps and diarrhoea" over a two-week period, officials said.
No deaths have been reported but high levels of E. coli were found in the water.
Tshwane has faced numerous outbreaks from waterborne diseases in recent years. In 2023, 29 people were killed by a cholera outbreak in a township just outside Pretoria.
That outbreak, in Hammanskraal, was linked to substandard water purification practices.
In 2025, officials confirmed 48 cases of typhoid in the same area east of Pretoria. The source of the outbreak remains unclear.
No cholera bacteria has been found in the latest cases.
The departments of water and health, in a joint statement on Monday, said 408 cases had been detected between 7 and 18 October in about five townships.
They said that lab tests "indicate that the illness has been caused by residents being exposed to contaminated water" from a local water treatment facility supplying water to several communities east of Pretoria.
Samples tested found norovirus, campylobacter, shigella and "other pathogens that cause stomach cramps and diarrhoea", officials said.
The team's early investigations found that local authorities had failed to warn residents about the contaminated water.
The water supplied to the area has been declared unfit for human consumption and authorities urged residents to only use it to flush toilets. Tankers have been dispatched to supply clean drinking water.
"Previously stored water should be discarded, and water containers must be disinfected using household bleach," officials said.