The city of Darwin is looking for a new water supply. 

Most of Darwin's drinking water comes from the Darwin River Dam, which was built in 1972.

But the Territory’s growing population, series of below-average wet seasons and effects of climate change are putting pressure on water levels at the Darwin River facility.

“Darwin River Dam has served us well for the last 50 years … but we need a solution for the next 50 years,” NT Water Security Minister Eva Lawler says.

“It's very much time that we diversify our water supply so that we can provide a secure water source moving forward.”

Two projects have been put forth as solutions to ensure water security for the Darwin region - Adelaide River Off-Stream Water Storage (AROWS) and the Manton Dam Return to Service (RTS). 

They are supported by a business case conducted by PriceWaterhouseCoopers. The NT government also supports the projects, but says federal funding is needed. 

It is estimated that Darwin will need an additional 11 million litres per year by 2050. 

The Manton Dam RTS project is proposed as a short-term solution, with development work potentially taking just three and four years.

Ms Lawler says work should start as soon as possible.

“The work around Manton Dam is that environmental impact work, it is around the design work that needs to be done … there's a new pipeline that'll need to be installed as well,” she said.

The AROWS project would take closer to 10 years.

“This project will be the biggest project undertaken by the Northern Territory government, by Power and Water, since the rail that was built quite a number of years ago,” Ms Lawler said.

There has been some concern that recreational use of the water bodies would be impacted by the plan. Ms Lawler insists swimming, water skiing and fishing would be allowed to continue. 

There is still a major question mark over who, if anyone, would be willing to pay for the plans.