Bakoven Beach has been temporarily closed to the public after an electrical failure at the Beta sewer pump station.
The City said the failure was caused by ongoing load shedding and that it was looking into how overflows at the pump station, near the small swimming area, could be prevented.
One option, the City said, was installing an emergency inverter or uninterrupted power supply (UPS) system at the pump station.
In the meantime, the beach has been closed, as contact with the water could result in potential gastro-intestinal issues, and health warning signage has been installed.
City Health said it would be taking water samples every day to test water quality until the levels are within the minimum requirement for recreational activities as determined by the National Water Quality Guidelines.