Drinking water safe, following blue green algae detection

Hunter Water's drinking water remains safe, and robust be effective, following a high detection of blue green algae in a sample collected from Grahamstown Dam.

The sample was collected from raw untreated water in the middle of Grahamstown Dam and contained high numbers of cyanobacteria (Microcystis), also known as blue green algae. Concentrations were much lower in samples collected on the same day from the northern and southern ends of the dam, including near the offtake to our water treatment plant. The sample collected in the raw untreated water at Grahamstown Water Treatment Plant (WTP) also had low levels.

The Grahamstown water supply scheme has robust monitoring and treatment processes in place for detecting and removing blue green algae and the current bloom does not pose a risk to our region's drinking water.

We manage our water supply through a multi-barrier catchment-to-tap process, ensuring that our drinking water is safe, reliable and high quality at all times.

Blue-green algae are a natural component of waterbodies like Grahamstown Dam and play a crucial role in the ecosystem by producing oxygen through photosynthesis. When conditions are favourable, such as high nutrient levels - following rainfall and runoff - and warm temperatures, cyanobacteria can form blooms, which can lead to a reduction in water quality and can pose risks to humans, pets and livestock if they drink the untreated water.