Water technology company Gradiant said on Wednesday it raised $225 million in its latest funding round, boosting its valuation to $1 billion which makes it a sector ‘unicorn’.

Unicorn is a term for an unlisted firm valued at $1 billion or more.

Boston-based Gradiant’s technology is used across a range of sectors including pharmaceuticals and semiconductors to help companies reduce water usage and clean up wastewater for reuse.

The company said the capital raised in the Series D round, backed by BoltRock Holdings and Centaurus Capital, would be used to continue its expansion, including into new markets such as the Middle East, as well as research and development.