How Much Water Do You Need for a Bushwalk? An Australian Guide
"Just take a water bottle" is the advice that puts walkers in trouble every Australian summer. The real answer to how much water you need for a bushwalk depends on how long you're walking and how hot it is - and there's a simple way to work it out before you leave.
Work it out before you leave, not halfway up the hill.
How Much Water Per Hour, Per Person
The baseline
In mild conditions with a light daypack, allow about half a litre per person for every hour of walking.
A typical day walk
A four-hour day walk means around two litres each.
It's per person
Kids need their own supply, carried where they can reach it.
Work out your walking time first
Estimate your walking time first, then do the maths. We've covered how in How Long Does a Bushwalk Take?.
Why Heat and Humidity Change Everything
Water needs don't rise gently with temperature - they jump.
Mild: about 0.5 L an hour
The baseline for a light daypack in mild conditions.
5°C warmer: about 0.75 L an hour
A rise of just 5°C can push your requirement up by half.
Hot: about 1 L an hour
Above roughly 32°C, long walks may simply be impractical - question whether the walk should happen at all.
Humidity counts as heat. These figures are based on how hot it feels, not just the forecast temperature, so a muggy day needs the hot-day amounts.
Climbing counts too - ascent raises your output and your sweat rate on any forecast.
In hot weather: start early, rest in shade through the middle of the day, and choose shaded or waterside tracks. More on heat in What to Do When the Weather Turns on a Bushwalk.
Signs of Dehydration to Watch For
Losing even a small fraction of your body's water measurably hurts your performance - you feel it as fatigue and flatness long before you feel it as thirst.
Watch for: thirst (you're already behind), headache, dark urine, unusual tiredness, irritability, and poor decision-making.
Sip regularly from the start of the walk rather than gulping when you're parched - small and often beats rare and large.
Eating matters too: salty snacks and fruit help your body hold onto the water you drink.
Why One Bottle Is Rarely Enough
A standard bottle is 600 mL - barely more than one hour's supply in mild weather, and well under an hour's worth in heat.
Assume there is no water on the track. Most Australian day walks have none, and creeks shown on maps are often dry.
Carry water in two or three containers rather than one - if a bottle leaks or is lost, you haven't lost everything.
It's always better to carry too much than too little. Water is heavy (a kilo per litre), and that's the one weight penalty worth paying.
Carrying, Treating and Refilling Water on Track
There's no single right way to carry it. Pick the setup you'll actually drink from.
Bottles
Simple, cheap, easy to share and refill. Two one-litre bottles beat one two-litre bottle.
Hydration bladders
The sip-as-you-go design genuinely helps people drink more - the trade-off is cleaning and refilling hassle.
Refilling
Never assume tank water at trailheads or campsites is available or safe - check with the land manager before relying on it.
Treating
Any water collected on track (creeks, tanks) should be treated before drinking: boiling, chemical tablets or a filter. For day walks, the better plan is simpler. Carry everything you need, as set out in Day Hike Packing List Australia: What to Take on a Bushwalk.
Not sure you've packed enough? Add one more bottle. You'll never regret carrying it.
Link to downloadable resource: Bushwalking Packing List
You'll find everything to pack for a day walk, sorted by category. Download or print the PDF with full details and keep it in your kit. The phone download version is a quick overview reminder list.
Source: water requirement figures from Bushwalking 101 - Water Needs, published by the National Parks Association of NSW.
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