One of Victoria’s wettest farming regions is running out of water.

The water storage at Leongatha, in Gippsland, is at 24 per cent and falling and residents are on stage four water restrictions.

South Gippsland Water is auditing local businesses, including the major dairy processing plant Murray Goulburn, to see if their water use can be reduced.

Meanwhile oil tankers could ship Tasmanian water to the mainland under a new proposal.

Environment company Solar Sailer will propose harvesting fresh water from a number of sites in the state’s north, when it meets the Tasmanian Government next month.

The company’s Robert Dane says selling water to major cities could prove a lucrative industry.

"For the smallest quantity required by any capital city which is 50 gigalitres this could be worth about $300 million and if there were a number of cities that wanted more than just the minimum amount then you are looking a potentially billion of dollars [in an] export industry from Tasmania for something that is already just flowing into the ocean," he said.