Icon Water anticipates restrictions are unlikely within the next two decades based on climate modelling, current storage and consumption levels.

This is partly because Canberrans changed their water habits during the eight-year millennium drought which broke in 2009, and are now using about 40 per cent less than they were prior to 2003.

However, an ACT government spokesman said if dry conditions persist, water restrictions could be brought in a lot sooner.

University of Canberra Institute for Applied Ecology associate professor of water science Fiona Dyer said despite the concerning lack of rain, it wouldn’t help farmers if Canberra was to be put on restrictions.

"The reality is that there are two different systems for water in the ACT and indeed most of Australia," Dr Dyer said.

"It is not common for our drinking water and our agricultural water to be coming from the same places"

Dr Dyer said most of the region’s farmers rely on private dams for their water, whereas the ACT has four drinking water dams that can hold about 277,900 million litres of water.

"Canberra and Queanbeyan use only a fraction of this in a year. At the moment we are using about 120 million litres per day," Dr Dyer said.

"So we’ve stored water from the recent wetter years and we are using it at the moment.

"We’ve had some good rainfall in recent years, so the dams have a good amount of water in them, but if the drought continues, the water levels will continue to drop and it is then that we will see water restrictions."

Dr Dyer said Canberra’s dams protect the city from restrictions during short, intense droughts but won’t protect residents from long droughts.

She said while it looked good at the moment, Canberrans need to be careful with their water usage to ensure it lasts that long.

“It will very much depend on the length of the drought we experience and with our local climate changing, then we may not always be able to rely on historical rainfall information to help with our future predictions,” Dr Dyer said.

“I think that the lessons of the millennium drought are still fresh in people’s mind. The millennium drought was long enough that people’s water use habits changed, our gardens changed and people are much more careful and aware about water use now.”

The millennium drought also led to the expansion of the Cotter Dam's capacity from 3.9 gigalitres to 78 gigalitres.

An Icon Water spokeswoman said that's meant Canberra can store more water than ever before.

"Icon Water's source water storages are currently at 68 per cent," the spokeswoman said.

"According to Icon Water projections, based on climate modelling, current storage and consumption levels mean water restrictions are unlikely to be required in the ACT within the the next 20 years."

An ACT government spokesman said the storage levels were "relatively healthy", despite the dry conditions.

"The initiative to construct the enlarged Cotter Dam and the community’s involvement in significantly reducing water use per person over the last 15 years have helped give us greater water supply security to buffer against extended dry periods," the spokesman said.

He said in a general sense, restrictions could be expected to be required when dam levels fall to about 35 to 40 per cent, which could be just two years away if similar dry conditions persist.

The Canberra community uses, on average, 300 litres per person, per day of water. Prior to the millennium drought, each person was using, on average, 480 litres per day.

"Continuing these behaviours will support the reduction of water use and consequently the need to restrict water use," the spokesman said.

Permanent water conservation measures are already in place in the ACT, described as "common sense rules" by Icon Water. These include: