Trains carrying 725,000 litres of water a day are the latest weapon to keep a drought-affected mine in inland New South Wales in production and keep jobs secure.

Key points: Southern Shorthaul Railroad carts 725,000 litres of water from Charbon Mine to Airly Mine each day on a 40km route

Southern Shorthaul Railroad carts 725,000 litres of water from Charbon Mine to Airly Mine each day on a 40km route Water trucks can carry an estimated 16,000 litres each load by road

Water trucks can carry an estimated 16,000 litres each load by road A senior NSW Government official says carting water by rail to parched towns is being planned

The Southern Shorthaul Railroad [SSR] company has started carting water between Centennial Coal's Charbon and Airly mines near Lithgow on a 40-kilometre route.

The unorthodox mode of water supply is not only securing coal production, but also jobs.

"They were so short of water that they were expecting to run out by September," SSR's chief executive general manager Chris Jones said.

"That would have meant that they would have had to cease coal production in the mine and, for them, that would have meant laying off 140 full-time staff."

He said his company had gone from hauling monster grain trains in the wake of drought to now carting water, which Mr Jones said had not been done for some time.

"There have been water trains run but probably not for a few decades now," Mr Jones said.

"Water trains would probably go back to the steam era in NSW and I understand maybe Broken Hill have seen some [water-carrying] trains, but not for several decades now."

How does it work?

Two crew members attach hoses to the water tankers at Charbon's loading station. ( Supplied: Southern Shorthaul Railroad )

Two crew members start by hooking up 10 hoses to 10 tank containers and repeating that process three times at the mine's Charbon facility.

It takes about two hours to fill all 30 carts with the 725,000 litres of water.

Comparing that to loads carted by road, water-carting services advertise capacities of around 16,000 litres a truck.

The unloading process takes about the same time as the water is poured into Airly's storage dam.

Water from the train is unloaded into Airly Mine's water storage near Lithgow. ( Supplied: Southern Shorthaul Railroad )

The mine received NSW Government approval last month to extract up to 170 megalitres a year from the defunct Charbon site.

The water comes from surface water run-off or from the Reedy Creek Dam.

The mine has a licence to pump almost double the amount it requested approval for.

In its environmental impact statement, Centennial Coal stated it would only use water on an 'as-needed basis' and that the average water deficit for a dry year at Airly was about 64 megalitres.

Trains could cart water to parched towns

Several communities in inland NSW have been facing the prospect of running out of water, with some supplies already dried up.

Mr Jones said rail could be used to transport more water to drought-affected businesses and communities.

"We have certainly got a lot of interest in operating water trains to drought-affected towns," he said.

A senior NSW Government official has told the ABC the prospect of carting water by train to areas in the west, such as Cobar, was in the "advanced planning" stage.

Editor's note (15/08/2019): This article has been updated to include extra information about the source of the water and correcting the spelling of Airly mine.