A drought-affected Queensland city may be forced to take millions of litres from Brisbane's water supply via a yet-to-be-used pipeline.
Toowoomba's three dams were at 35.7 per cent on Thursday - the lowest level since before the 2011 floods.
When the level falls below 40 per cent, the Regional Council is permitted to take water from Wivenhoe Dam - the main reservoir for Brisbane and Ipswich - via the $187 million Toowoomba Pipeline.
While the council has never pulled the lever on the 38-kilometre pipe in the nine years since being laid, AAP understands it will discuss doing so at a meeting next week.
It can take up to 10,000 megalitres per year to supply its 110,000-strong population, with Wivenhoe Dam sitting at 60.3 per cent capacity with more than 700,000 megalitres.
Toowoomba Regional Council has been contacted for comment.
It comes as the severe Queensland drought has forced the inland Southern Downs Regional Council to introduce extreme water restrictions.
About 35,000 residents near the NSW border have already been restricted to four-minute showers.
But, from Thursday, households have been told to further reduce their daily water usage to just 120 litres per person, less than half the national average.
Average daily water usage nationally is 274 litres per person, according to the Department of Environment and Energy.
Mayor Tracy Dobie said the ongoing drought has hit the region hard and extreme measure were needed to preserve the region's dwindling water supply.
"Even in drought, generally, there's enough rain spasmodically to put water in people's tanks," she told AAP.
"But we have not had a drop in four months. This is the driest summer ever recorded.
"This means our domestic water supply - our dams - is now having to supply double the amount it was constructed to supply."
The council's main reservoir, Leslie Dam, is currently at 7.2 per cent capacity.
Water supplies at Storm King Dam and Connolly Dam have fallen to 41 and 45.2 per cent respectively.
The Southern Downs was drought-declared in May last year following extremely dry conditions when little rainfall fell for many months.
The extreme water restrictions were introduced at a special council meeting on Wednesday.
Rural residents accessing water from the Stanthorpe and Warwick standpipes will also have their access to supplies restricted.
They're now limited to purchasing a maximum of 1000 litres per fill, capped at 3000 litres per week.
