Locals stunned as water mysteriously turns red near Sydney Harbour

An investigation has been launched after mysterious red water was discovered near Sydney Harbour, leaving experts puzzled about its source.

Residents in Sydney were shocked to discover mysterious red water in a bay that runs into Sydney Harbour, leaving experts puzzled about its cause.

The ruby red water was discovered on Careening Cover, flowing through Milson Park in Kirribilli on Monday.

Residents in Sydney were shocked this morning to discover mysterious red water in the bay that runs into Sydney Harbour, leaving experts puzzled. Picture: 7News

The wine-coloured water was reported to the North Sydney Council, and while there is no known source for the change in colour, the council suspects it was caused by plumbers’ dye.

“Council is aware of the red water flowing into the harbour from Milson Park, and officers have investigated but have not been able to find the source,” a spokesperson explained.

The incident has been reported to the NSW Environmental Protection Authority.

An investigation by the EPA is currently underway to locate the source of the dye.

“North Sydney Council alerted us to what appears to be red plumbers’ dye in a drain at Kirribilli this afternoon and we are currently investigating the potential source,” a spokesperson for the EPA said.

It’s believed the red was caused by plumbers’ dye, also known as fluorescein, a solution commonly used in plumbing or drain testing that dissipates quickly once diluted.

“Fluorescein has low toxicity but even small amounts can be highly visual and for this reason its use should always be minimised,” the spokesperson told NewsWire.

There is no known cause for the red water. Picture: 7News

This is not the first time Careening Cove has been subjected to water of a different colour.

In September, the body of water turned “fluorescent green”, leaving residents and the NSW Fire and Rescue baffled.

While it is believed the bright green liquid was caused by plumbers’ dye, with numerous points of entry in the cover, it would be very difficult to find the exact source.

Anyone concerned about possible water pollution should contact the EPA’s 24/7 Environment Line on 131 555.

Originally published as Locals stunned as water mysteriously turns red near Sydney Harbour