The Opportunities Party is pledging to resolve the issue of who owns water.

It's made the promise in a new water policy announced today that aims to impose water use charges on commercial users of the resource.

The Opportunities Party said it'll seek to settle the issue of water ownership once and for all with regard to the provisions of the Treaty of Waitangi.

It said it'd be a pre-condition for establishing a commercial model for water use.

However, the Government says water is already charged for.

Prime Minister Bill English said a lot of councils do charge for water now.

"We have a long history of charges for the use of water, which is not the same as ownership of the water, and that's proven to influence how people behave often making them more sensible in how they use water," said Mr English.