“These ‘do not swim’ black flags will be in place until Friday afternoon. A black flag means there is a very high risk of illness from swimming.
“You won’t see a black flag at the beaches, rather the flags are displayed on the Safeswim website,” Watercare said in an online post on Wednesday.
Safeswim said overflows are more common in wet weather but can happen in dry weather if pipes are blocked or damaged.
Wastewater overflows occur when sewage spills out from gully traps, manholes, engineered overflow points or pump stations. It then flows into backyards or waterways and the sea.