Every political cycle, a cavalcade of federal and state politicians dust off their Akubras, RMs and plaid shirts and head north, ready to pledge the nation's drought-ravaged farmers everything but actual rain.

The possibility of piping the water resources of northern Australia to quench thousands of thirsty southern agricultural paddocks has been floated by a litany of leaders keen to make use of the annual downpours of the tropical wet season.

But how plausible is the idea of pumping water from the Northern Territory down south to ease the dry soils of pastoral properties in Queensland, NSW and Western Australia? Or is it just a pipe dream?

"There's been a hell of a lot of coverage of drought," Curious Darwin questioner Derek Whittle said.

"I thought, 'why can't we relocate this'?"

Curious Darwin is our story series where you ask us the questions, vote for your favourite, and we investigate. You can submit your questions on any topic at all, or vote on our next investigation.

This question was the winner of a public vote, with more than 2,300 of you wanting to know the answer along with Derek.

Piping water from the north to southern Australia isn't a new idea. ( Supplied: Adobe Stock )

According to scientists, water experts, and those who have been involved with some of the Top End's biggest-ever water infrastructure projects, the idea could work — in theory.

But no government would ever have the cash surplus needed to fund it, with experts warning any such a plan would cost billions and billions — even trillions — of taxpayer dollars.

And besides, is the notion that the NT has an endless supply of rainwater just a myth, anyway?

Project would sink billions

Although nearly 2 metres of rain falls each year in Darwin, the city does not have the infrastructure in place to capture enough of it and pump it out, Power and Water Corporation's Jethro Laidlaw said.

"We would need massive dams," he said.

"We already have Darwin River Dam, but we sort of need all of that for Darwin.

"We would need to build a massive dam — which is expensive — and we would have to build the pipes that would take the water there, which are extremely expensive … it would cost billions of dollars."

Despite the walls of water hitting Top End soil each year, "it's incredibly expensive to pump it to southern parts of Australia", CSIRO research scientist Andrew Ash said.

"Just the energy requirements on an operational scale means that it's very expensive, let alone the capital costs of building channels or pipelines to southern Australia."

Darwin River Dam's water is needed to service the local community. ( Supplied: Power Water Corporation )

The Lake Argyle argument

Not far from the outback West Australian town of Kununurra lies a massive man-made body of water, which contains the volume of 18 Sydney Harbours.

This feat of human ingenuity is called Lake Argyle and was built over a few years from 1969, with the idea it would be used to help fuel the Kimberley's growing demand for agricultural irrigation, which it has achieved to varying degrees of success.

But could this water ever be harnessed to help douse the higher populated electorates around 3,000 kilometres away in Perth?

Probably not.

Water from Lake Argyle in WA can't be piped south due to the cost. ( Supplied: Adobe Stock )

Charlie Sharp is the owner of Lake Argyle Cruises and Tours, and his father worked on the project.

He said the idea of piping the water south is "an age-old question that comes up every time there's a state or federal election", but is probably just not feasible.

"Every year, it started back in the '80s with [former WA MP] Ernie Bridge — he considered the Kimberley pipeline, piping water from Lake Argyle or Ord River Scheme," Mr Sharp said.

"[He] also [considered] potentially damming the Fitzroy River and piping water down to Perth and the southern states and the drier areas of the desert.

"The one hindrance — every single premier of Western Australia has spoken about this for the past 35 or 40 years — the hindrance has always been not the cost of building it … the problem is actually the cost of pumping the water down there.

Former WA MP Ernie Bridge was one of the first to consider piping water from Lake Argyle. ( Supplied )

"It would be a great infrastructure project, but … I just don't think Australians are probably willing to pay the price."

CSIRO research scientist Cuan Petheram said studies of the Lake Argyle proposal had proved that the idea would be too cost-prohibitive.

"On a technical level it all comes down to cost," Mr Petheram said.

He cited a report commissioned by the West Australian government in 2006 called "Options for bringing water to Perth from the Kimberley".

"There was a study done in Western Australia a few years ago, where they looked at pumping water from the Kimberley down to Perth, and they looked at a whole range of options," Mr Petheram said.

"They looked at pumping, they looked at canals, they looked at shipping the water down, they looked at towing the water down in great big balloons behind boats, they looked at desalinisation.

"And of all the options, pumping and canals were by far the most expensive."

Darwin the water wastage capital of country

The Territory's sparse population consumes 43 billion litres of water annually and loses millions of litres on leaks and irrigation.

With a population of just 120,000 in Darwin the figure is staggering; as Mr Laidlaw said, "per capita, that's very high water use".

It breaks down to an average of 400,000 litres each year for Darwin households, about double the Australian average.

"It's significantly higher than other towns with a similar climate such as Cairns," Mr Laidlaw said.

"Like a house, if you're turning your taps on and off and you've got three kids who are having showers and you've got a washing machine and you've got all of those things a normal house uses, you're very hard pressed to use more than 200,000 to 300,000 litres per annum.

"And in Darwin we use 400,000 or 500,000 per annum, per connection."

NT households consume 43 billion litres of water per year, a very high rate. ( ABC News: Isabella Higgins )

He said of these Darwin water usage figures, 70 per cent is being used in garden irrigation or being lost through leaks.

Earlier this month, the ABC revealed that the tiny Tiwi community of Bathurst Island, population about 1,800, was consuming an estimated 2.5 million litres of water per day, largely believed to be because of leaks and running taps.

High water usage is visible even when one walks down the main streets of Darwin CBD; council sprinklers can often be seen broken and running off into concrete gutters.

A shade structure rigged with misters on Cavanagh Street intended to cool down city walkers sprays out 2,000 litres of water per day.

NT Infrastructure Department project director Lyle Hebb conceded this use to be a "reasonable amount of water", saying it was "somewhere in the range of about 9 litres a minute when they're running".

And much of that water hardly hits the ground.

How much water can Darwin actually spare?

Despite the high volume of rain that pummels the Top End during monsoon season — about 1.7 metres worth hits Darwin each year — the region has an extremely high evaporation rate, with Darwin's dam losing about 2 metres' worth of water annually.

Despite its high rainfall, Darwin needs every drop of water it can get. ( Supplied: Adobe Stock )

Darwin River Dam can hold well in excess of the 43 billion litres consumed by thirsty Top Enders each year, Mr Laidlaw said, but a lot of it evaporates, meaning water is a more finite resource for the Territory than it may seem on first glance.

"If we get a poor wet season or a couple of poor wet seasons in a row, then Darwin could be in real trouble," Mr Laidlaw said.

The dry climes of mid-year mean the NT needs to suck up every drop it can get.

CSIRO's Mr Petheram said there would be a huge social backlash involved with ever trying to suck the Top End's water down south.

"On a social level, I've been working in northern Australia for quite a while, and have had various interactions with various communities across the north," he said.

"And there is a pretty strong feeling that if people down south want our water, they can come up to northern Australia.

"The water's up here, and it has to be used up here if it's going to be used at all."