Ellalong Lagoon near Cessnock could be a reservoir for millions of litres of wastewater from Sydney and Newcastle under a bold water recycling plan that would drought-proof the Hunter.
Hunter-based water security analyst Joe Taranto says about 400 megalitres of wastewater that is presently dumped into the ocean at North Head would be redirected north via a gravity assisted subsea pipeline.
Another 50 megalitres of wastewater would enter the pipeline at the Burwood wastewater treatment plant.
From there it would be pumped via a pipeline along the Hunter River to Hexham and on to Kitchener. It would then travel across a 10 kilometre series of gabions filled with stones before reaching Ellalong Lagoon.
"Water exposed to sunlight while running over different sized gravels and stones does not have to travel far to be suitable for most purposes," Mr Taranto, who spent more than a decade building small sewage treatment plants, said.
Ellalong Lagoon would need to be deepened for the project.
From the lagoon the water would flow into the river system by gravity to Millfield, Wollombi, Paynes Crossing, Broke, Bulga and Warkworth.
It would be available to the water-intensive power generation, mining and agriculture sectors.
Mr Taranto has been working on the project since 2013.
The plan to send water to the Ellalong Lagoon, rather than directly to the Upper Hunter via a pipeline, is the scheme's latest evolution.
Water officials who have met with Mr Taranto have said the project, which has an estimated price tag of $2 billion, is too expensive and would provide too much water to the Hunter.
But Mr Taranto begs to differ. He cites several successful, similar-scale water recycling projects in Israel as examples of what could be achieved.
He argues that his proposal represents better value for money and is more environmentally sustainable than the options listed in the Lower Hunter Water Plan.
"The amount of water that gets pumped from Burwood into the ocean each year is the equivalent of one Chichester Dam," he said.
"This scheme is about the same cost as building two new dams; but there's not much point building a new dam if you don't have water to fill it with."
In addition, he says the scheme would mean it would not be necessary to build a proposed 15 megalitre desalination plant at Belmont.
Hunter Water will start building the $100 million project if water storages reach 35 per cent.
"Temporary desalination units are a band-aid solution," Mr Taranto said.
"Obviously my project would cost more but it represents much better value for taxpayers."
"Everyone knows if a desalination plant goes in the cost of water is going to go up."