I was a bushwalker for many years. On occasions the leader would instruct the party to carry water all day until we got to camp by a river that evening. Before the wine cask was invented, such walks were the domain of the hardy. But the four-litre plastic inner lining of the cask, when half full, provided a flexible water container which could be fitted snugly into the gear in a walker's backpack.
Then, when we got into camp, and during a prolonged drought, we would find that the river had not flowed for weeks. The water would need to be boiled for 10 minutes in a metal billycan to ensure all spores had been killed. And, before retiring to one's tent, at least a litre would need to be boiled for carrying out in the wine skin the next day.
Water is life. I always carried an emergency supply of iodide tablets for getting the bugs in stagnant water down to a low enough number so that I could drink the vile liquid without vomiting and losing even more moisture from my body.
Also, in bone-dry country there may have been a short shower during the night - or if it was an exceptionally cold night, there may be some melting ice in a rock crevice. So, I had a length of small diameter plastic tubbing which would enable me to suck water out of a tiny puddle or a crack in rock.
None of this technology was available to the Aborigine. How, then, did he survive? The answer is that mostly, he didn't.
Where I live, there once lived the Wodi Wodi people who relied substantially on shellfish to survive. In a dryer-than-usual year there is no water at all in the creeks. So, I ask myself, what would the Wodi Wodi have done? There was only one thing to do, and that was to cross over the ridge to the Woronora River. Its flow can be counted upon - except that once I saw it cease to flow.
There would have been a few times over the past 50,000 years when that river would have been reduced to a string of stagnant and undrinkable pools with the bodies of emaciated humans on its banks. Once the water runs out at one's favourite source, there can be no exploring for another source as exercise when severely dehydrated leads quickly to delirium and death.
Without fresh water in the quantities the body needs to live, you die a dreadful death. One can imagine the mounting fear as the Aborigines witnessed the supply of drinkable water shrink to nothing.
As a natural conservative action, urine flow ceases - but then the body cannot excrete its toxic waste. More detrimental is that as moisture loss is reduced from the skin as a natural conservative action, the body temperature quickly rises to a fatal degree. And, as the interior of the lung and the atmosphere is an open physical system, the body cannot prevent the accelerated loss of water into air which has zero humidity.
What technology did the Indigenous use?
They had water buckets made of woven leaf. These utensils could only be used to transport maybe four litres of water over very short distances and over flat country. They had no way of storing any more than about five litres of water in a well painstakingly ground out of a rock. That is barely enough to keep a man alive for two weeks - let alone a tribe for a year.