Human remains found at a water treatment facility in the Blue Mountains have been identified as missing woman Cecilia Devine.

The 42-year-old Newcastle woman had been missing for almost eight months, with police saying they held grave concerns for her welfare at the time of her disappearance.

Staff at a water treatment facility in Katoomba found remains in the Upper Cascade Creek dam at 12pm on March 18. After extensive testing, they were identified to be Ms Devine.

She had been reported missing from Waratah on September 5, 2018.

Police are now treating the discovery of her remains as a homicide and have launched Strike Force Eking to investigate.

As part of ongoing inquires, investigators have released CCTV footage of Ms Devine walking from a hotel in Katoomba Street, Katoomba, the day after she was reported missing.

She was wearing a bright yellow cardigan, black pants and carrying an orange handbag.