Increase your chance of survival
Water, warmth, signals, shelter, and food are widely recognised as the
top survival priorities in a wilderness emergency. Regardless of where you are hiking,
water is the most critical and time-sensitive of these.
If you have access to sufficient water, your chances of surviving long enough to be located by search teams, or to self-rescue, increase dramatically. Without water, physical and cognitive decline can occur rapidly, particularly in hot, dry, or exposed Australian environments. If you do not have water, finding a safe supply quickly becomes a priority.
A few important water facts
- The human body is made up of around 60 percent water
- We do not produce water and must replace losses through drinking fluids
- We lose water through sweating, breathing, and urination
- As fluid losses increase, physical performance and mental clarity decline
- Thirst is a useful signal, but it often appears after fluid losses have already begun
- Dark urine, reduced urine output, dizziness, fatigue, and confusion are common signs of dehydration
Dehydration is not a single moment. It is a
progressive loss of body water over time.
How much water do we need?
Daily water needs vary widely depending on body size, temperature, terrain, pack weight, pace, and individual sweat rate.
As a general baseline, many adults require around
2 to 3 litres per day under normal conditions. During hiking, especially in warm or hot weather, requirements can increase substantially.
Research shows that a loss of as little as
2 percent of body weight through dehydration can impair physical performance and cognitive function, including decision-making and problem-solving. These effects are particularly relevant in remote environments where good judgement matters.
How should water be consumed?
There is no minimum volume of water that must be consumed in a single drink to hydrate the brain or other organs.
Water absorbed from the gut enters the bloodstream and contributes to overall hydration regardless of whether it is consumed in small, frequent amounts or larger drinks at breaks.
What matters is
total fluid intake over time relative to fluid losses.
Practical hiking guidance supported by exercise physiology research includes:
- Drinking regularly throughout the hike
- Taking small, frequent drinks while walking, if convenient
- Drinking larger amounts at rest breaks, if preferred
- Avoiding long periods without drinking, followed by attempts to “catch up”
Both sipping and drinking larger volumes are effective when they replace ongoing losses.
Can sipping water lead to dehydration?
No. Sipping water does not cause dehydration.
Dehydration occurs when
fluid intake does not keep pace with fluid loss, regardless of how the water is consumed.
Problems arise when hikers drink too little overall, often because they underestimate sweat loss, delay drinking until thirsty, or ration water unnecessarily.
There have been tragic cases where individuals carried sufficient water but consumed far less than their bodies required under extreme conditions. These cases reflect
insufficient intake, not the act of sipping itself.
Water loss through perspiration
Sweating is the body’s primary cooling mechanism. Without adequate fluid replacement, core temperature rises and the
risk of heat exhaustion and heat stroke increases.
Under high heat and exertion, sweat losses can be extreme. Laboratory studies have shown that during sustained activity in very hot conditions, individuals can lose
up to one litre of fluid every 30 minutes.
While these conditions represent the upper end of exposure, they illustrate how quickly dehydration can occur if fluid intake does not keep up with losses.
Can you drink too much water?
Yes, but it is uncommon.
Drinking excessive amounts of plain water without replacing electrolytes over long periods can dilute blood sodium levels, leading to
hyponatremia. This condition can be dangerous and, in rare cases, fatal.
Hyponatremia is most often associated with:
- Prolonged endurance activity
- High sweat losses
- Large volumes of water consumed without electrolytes
- Slow or forced drinking beyond thirst cues
For most hikers, the greater risk remains
under-hydration, not over-hydration.
What are electrolytes and why are they important?
Electrolytes are minerals such as sodium, potassium, calcium, and magnesium that help regulate fluid balance, nerve function, and muscle contraction.
During sweating, electrolytes are lost along with water. On longer hikes, hot days, or multi-day trips, replacing electrolytes can help maintain hydration and reduce fatigue and cramping.
Electrolytes can be replaced through:
- Food
- Electrolyte drinks or powders
- Oral rehydration solutions
How long can you survive without water?
Survival without water depends on temperature, activity level, health, and exposure.
In extreme heat, dehydration can become life-threatening within
24 hours or less. In cooler conditions with minimal exertion, survival may extend to several days, but performance and judgement deteriorate well before that point.
Food deprivation is far less immediately dangerous than lack of water.
Planning is critical
Good planning remains the most effective safety strategy.
Knowing how much water you are likely to need, where reliable water sources are located, and how conditions may affect your fluid requirements is essential before stepping onto the trail.
Carrying sufficient water, drinking regularly, and adjusting intake based on conditions can significantly reduce risk when hiking in the Australian outdoors.
About Bob Cooper
Bob Cooper is one of Australia’s most experienced bushcraft and survival instructors. Born and educated in Western Australia, he has delivered Outback Safety and Survival courses since 1990 and is widely regarded as a leading authority on desert and remote-area survival.
Related articles
Water and Hydration
Overhydration and Hyponatremia
How to spot and treat heat exhaustion
Tips for avoiding heatstroke when hiking
Don’t have to look very far to find deaths from over-hydration. This one from my neighbourhood, for example:
“Bushwalker died from drinking too much water” https://amp.smh.com.au/national/bushwalker-died-from-drinking-too-much-water-20120917-2621c.html
It might be more useful to quote the statistics for dehydration/over-hydration deaths, rather than the appeal to experience used here.
Note that deaths from dehydration are most common in the elderly, and usually in their own home or care facility.
Thanks for your comments Julian. Completely agree about the risk of Overhydration and Hyponatremia. Fatal hyponatremia in hikers is rare, but sadly it has claimed the lives of some. Overhydration should be something that all hikers are aware of and take seriously but it’s important to keep the risk of ‘overhydration’ in perspective.
One study of ‘higher risk’ athletes who developed symptomatic hyponatremia were participating in distance running events of 42 km and triathlons lasting 9–12 h. In these events, symptomatic hyponatremia still only occured in 0.1–4% of the participants. Conversely, dehydration has been estimated to occur in up to 80% of athletes in activities such as team sports, tennis, hiking and endurance events.
You can read more about overhydration here. https://www.trailhiking.com.au/overhydration-and-hyponatremia/
Thanks for the article, it was a good read! Another tip for viewers would be to stock up on water as soon as you see it rather than waiting. For example, on a multi-day hike in Mitchell River I got lazy and planned to refill my water bladder the next morning instead of that evening at camp, and by then the water had turned brackish and muddy from overnight rainfall (and had to drink it as was the only option). So always best to stock up when you can overnight when the opportunity for clean water arises and you can always discard any excess later on before continuing the hike.