Once they reached the watering hole, they used a T-shirt to filter the unclean water, she said. Ms McBeath-Riley was found near her vehicle but her companions are still missing.
Tamra McBeath-Riley, 52, was rescued late on Sunday afternoon, but her companions Claire Hockridge, 46, and Phu Tran, 40, remain missing in punishing terrain south of Alice Springs.
The group were travelling in remote territory just south of Alice Springs when they found themselves stuck in the bed of the Hugh River.
They took Ms McBeath-Riley's dog Raya, a female Staffordshire bull terrier, with them.
The three set out from Alice Springs for an afternoon drive on November 19 and their auto became bogged in a riverbed southwest of the town.
"During the day it's just really hot so we dug ourselves under the auto during the day into the sand".
They used up all their supplies of water, as well as some iced vodkas, biscuits and beef noodles they had in the vehicle.
Fearing the worst as days passed and no one came to their rescue, they separated sometime around Thursday, hoping one of them would find help and guide rescuers to the others. Mr Tran and Ms Hockridge planned to walk towards the highway.
For one desperate week they stayed together, gathering the dirty water, boiling it when they could and using a shirt to strain out the sediment, Supt Vicary said.
In the Australian outback, people and towns are few and far between, and Pauline Vicary, police superintendent for Australia's Northern Territory, said the unforgiving region made the search especially complicated.
'She's had a fairly traumatic period of time.
Authorities found the ute and from there tracked the group to the Finke River site where they found water, locating Ms McBeath-Riley there without her friends.
A woman missing in the northern outback for nearly a fortnight says she drank water from a cattle watering hole to stay alive and is "worried to death" about her companions.
McBeath-Riley told reporters outside a hospital where she was treated for dehydration Monday that when help arrived, she figured Hockridge and Tran were also safe. In January, German tourist Monika Billen was found dead near Alice Springs after she disappeared while on a hike.
She said she had assumed her companions had already been found and that "to find out that's not the case is worrying". Supt Vicary said officers had yet to begin searching the area by foot.