Why Treat Water?

What are the reasons for treating water and when to do it?

Learning from a teacher who has stopped learning
is like drinking water from a stagnant pond. Indonesian proverb

The aim of water treatment is to remove contaminants or reduce them to a concentration that means the water is safe to drink. Safe drinking water does not have to be sterile, and can contain organic and inorganic matter that the body can tolerate. Contaminants include sediments and pathogens (bacteria, viruses, protozoa, larger organisms (worms) or salts and toxins (fertilisers, heavy metals). Most commonly, water supplies are contaminated by human or animal excrement, or occasionally a dead animal carcass ends up in the water supply (e.g. cattle crossing a river). Contamination can also occur in the form of pollutants from human infrastructure such as mining or farming.

Typical water borne diseases Signs and symptoms of typical water borne diseases

Common pathogenic parasitic infections in humans include Giardia, Cryptosporidium (protozoans) and E. coli (a common bacteria), all of which are transmitted via contaminated water of poor hygiene. Symptoms vary from stomach cramps and fatigue though to bloating and diarrhoea.

A pathology test can quickly distinguish Giardia from Cryptosporidium, but on a bushwalk the symptoms of stomach and intestinal upset are very similar. Instead, these types of infections are generally referred to as Traveller’s diarrhoea. Good hygiene practice and care of food and water are the best ways to prevent getting sick in the bush. Prevention is better than cure!

Water, to treat or not to treat? The decision process involved

There is no practical way to be sure if the water is safe to drink, so if in doubt treat it. In general, on day walks that start from home and built up areas take all water you need from a tap. Day walks are often close to farms, houses, mines or other places that mean the water is likely contaminated. Also, on most day walks it is easy enough to carry enough water for the day. The exception of longer day walks especially when it’s hot. You may need to plan for water collection and treatment.

On overnight and longer walks, it’s probable that water will be of a higher quality, but again there is no way to be sure. As the number of people walking or travelling through the remote areas increases, so does the chance of water being polluted by human waste. For example, parts of Tasmania’s Overland Track have water pollution, from human wastes. Some people choose to drink straight from creeks where there are no more campsites, tracks, huts or other potential pollutant sources, upstream. The risk of getting sick whilst in remote areas comes with significant consequences, generally best to err on the side of caution and treat the water.

Individual health and immune strength is also a factor: everyone’s immune system is different, and tolerance levels to pathogen contaminants vary. Diseases that affect the immune system like HIV and diabetes mean that some people may be much more susceptible to pathogens. Pregnant women are also at higher risk. Therefore, individuals who are immunocompromised (i.e. an impaired immune system) would be wise to take extra precaution and treat all water and to speak with their doctor about the best methods for them. Likewise, overseas travellers often don’t risk drinking the same water supplies as locals because their immune systems have not had time to build adequate resistance. This is often why travellers are advised to drink bottled water only.

Infection of waterborne pathogens can also occur from using contaminated water to wash or cook or from physical contact with an infected person, “hand to mouth” transmission. According to a study of the risk of giardiasis from consumption of wilderness water in North America, the incidence of giardia in wilderness walkers is high, however, the infections are more likely caused by poor hygiene rather than contaminated water[note]Welch TP (2000). Risk of giardiasis from consumption of wilderness water in North America: a systematic review of epidemiologic data. International Journal of Infectious Diseases 4 (2): 100–103[/note]. Regular use of antibacterial gels after toileting and before food preparation and consumption on a bushwalk can reduce the likelihood and spread of infection.

But while the body can fight some pathogens to some degree, it’s a different story for some materials that can accumulate in the body. Long-term use of water contaminated with heavy metals can have severe health implications because the metals can bind to cellular matter and interfere with essential processes[note]Landis, WG; Sofield, RM; Yu, M-H (2000). Introduction to Environmental Toxicology: Molecular Substructures to Ecological Landscapes. 4th: CRC Press[/note]. Heavy metals have carcinogenic properties and can interfere with respiratory and circulatory systems. Unlike water sources that are pathogen-infected, water sources that contain heavy metals cannot easily be treated to make them safe in the field and should, therefore, be avoided unless in an emergency.

In short, choosing to treat water comes down to good judgement, if in doubt treat it and encourage people in your group to use good personal hygiene practices.

Water Contaminants

What things need to be removed in water?

It is not possible
to add pesticides to water anywhere
without threatening the purity of water everywhere Rachel Carson, 1962

Water can be contaminated by living things such as bacteria, viruses and protozoa, and non-living things such as sediment, dissolved tannins, fertilizers and heavy metals. The differing sizes and nature of these contaminants mean that some water purification methods work on some contaminants but not others.

Without optical aids, it’s only possible to identify large sediment. Anything smaller than what the naked eye can see requires more complex microbiological tests to determine their presence. In some cases, water is coloured by soluble vegetation or peat matter, known as tannins. Tannin coloured water is perfectly fine to drink without treatment, despite what some people perceive as an unpalatable colour.

Large sediments How to deal with water containing large sediments

Large sediments are any visible biological material in or floating in the water source. These include leaves, sticks, mud; and other organic debris such as plant and animal matter.

Removing sediments or other large organic matter may make subsequent water treatment more effective. This is particularly true for chemical treatments where the active chemical particles tend to bind to organic matter, thus reducing their effectiveness.

An effective way of removing sediments is to filter the water through cloth. Collect water in a large billy and filter it into smaller containers. Clothing fabric filters well because they are strong enough to catch organic material but still allows the much smaller water particles through the holes in the fabric. A hat or bandana works well.

Filtered water still contains pathogens, so a decision needs to be made if further treatment is required.

Pathogens How to deal with water containing pathogens

Pathogens can make humans sick by challenging the immune system. Some pathogens kill cells or disrupt cell function, and others produce toxic waste products. Sometimes pathogens multiply so quickly that they crowd out the host tissues, disrupting normal function. The immune system fights back with chemical secretion, antibodies and fever, a heat response aimed at killing pathogens.

Consuming too many pathogens can cause mild to severe illness in humans and can lead to death, particularly in parts of the world where people do not have access to clean drinking water[note]Montgomery, M. A. & Elimelech, M. Water and sanitation in developing countries: including health in the equation. Environment Science Technology 41, 17–24 (2007)[/note].

Pathogens most harmful to humans include microscopic viruses, bacteria and protozoa as well as larger organisms such as worms.

Viruses are much smaller than bacteria or protozoa, and need to occupy another living cell to replicate. They are infectious agents that can attack a variety of living things from bacteria and protozoa through to animals and plants.Virus background

Bacteria are single-celled prokaryote organisms that are a few micrometres in length. Bacteria were one of the first forms of life to appear on earth, and are renowned for being able to survive in soil and water as well as extreme conditions such as radioactive waste and acidic springs.
Green Bacteria Colony

Protozoa are single-celled eukaryote organisms that are generally bigger than bacterial cells and contain different cell contents.

Parasitic worms are more evolutionarily complex than viruses, protozoa and bacteria being multi-celled eukaryote organisms. Although they can survive independently, many species use another host organism to reproduce and spread. They can enter the human body in cyst or adult form via food and drink or bites from insects like mosquitoes and often reside on the skin or in the intestines. Humans suffer discomfort and illness from such infections including diarrhoea, fatigue and skin rashes.
Parasitic nematode worms (roundworms) Ascaris lumbricoides, male

Pathogens can generally be removed by:

Toxins How to deal with water containing toxins

Toxins can make people really unwell by poisoning the body. Sometimes, toxins only need to be in small concentrations to cause problems. In other cases, it’s the accumulation of toxins over an extended period of time that causes health problems. This is particularly a concern for people ingesting water from industrial run-off in areas that do not have adequate regulation of clean drinking water.

Toxins of concern include fertilisers, made of nitrogen, phosphorous and potassium. These can cause serious environmental damage and health risks to humans when found in waterways. Once fertilisers reach waterways, they enrich nutrients so much that some plant populations explode in quantity. Large amounts of blue-green algae is a sign of this Eutrophication process, and this algae produces toxins which go on to poison animals and humans alike.

Heavy metal runoff is another toxin of concern. For example, mercury runoff into water systems occurs via industry processes including coal and gold mining, Chlor-alkali plants and Trash incinerators. Mercury poisoning in humans can lead to itchy skin, swelling and skin discolouration, and at extreme levels of exposure, muscular weakness and mental confusion. Mercury poisoning is usually caused by consumption of aquatic produce where mercury has bioaccumulated. Mad Hatter disease was a chronic syndrome among hat makers who had prolonged exposure to mercury vapours. The “Mad Hatter” from Lewis Carroll‘s Alice’s Adventures in Wonderland is renowned for his eccentric behaviour.

Toxins cannot be removed by chemical or UV treatment, and boiling will only concentrate the toxins further. Instead, chemicals must be filtered out, a process that requires special equipment as it requires filtration at the atomic scale. While some hiking filters may claim to reduce toxins such as mercury, they are unlikely to remove such contaminations completely.

From a practical sense, if pushed for water supplies, drinking low levels of water containing toxins is probably not going to have ongoing effects, but continual use is unwise. It’s dangerous to consume fish or other aquatic food from these systems because toxins tend to bioaccumulate in aquatic organisms to levels that are very dangerous.

Salts How to deal with water containing salts

Saltwater typically refers to ocean water with high concentrations of sodium chloride. Saltwater is unpalatable and drinking it will lead to dehydration. But drinking water also contains other types of salts at palatable levels.

Tap water contains some salts, which varies with the source. This is why tap water tastes funny when drinking from a source that’s different to usual. In appropriate quantities, the following salts are not a problem:

  • Calcium and magnesium – these describe the hardness of water
  • Sulphates such as magnesium sulfate, calcium sulfate or sodium sulphate
  • Iron from rock deposits and
  • Chlorides, either naturally occurring or from industry.

As with toxins, salts are challenging to remove in the field as the process requires atom-sized filtering systems. Small hand-held units use portable reverse osmosis to purify water. The Katadyn Survivor 06, which produces 0.89 litres of water per hour at a pumping frequency of 40 pumps per minute. Given the effort required, it’s better to select a freshwater source where possible and only use desal unit in an emergency situation.

Water Treatment Methods

What treatment methods are most appropriate for various contaminations

When the water starts boiling, it is foolish to turn off the heat. Nelson Mandela

There are a number of ways to make water palatable in the field, each with different merits on ease and effectiveness of decontaminating water. Often, it’s worth having a few options available in case one fails.

Editor’s pick: Lightweight UV radiation pen with a backup of chemical tablets.

Heat How to use heat to treat water

The boiling method is used for killing living contaminants (bacteria, viruses and protozoa) found in a water supply. It does not sterilise the water, but instead, damages living pathogens enough to kill or prevent them from replicating.

Water must be heated to boiling point 100℃ at sea level then have a rolling boil for at least one minute, and three minutes if above 2000 metre altitude. Since water boils at a lower temperature at higher altitudes, the extra time accounts for the difference in temperature.

Advantage: no specialised equipment required since billy and stove is already part of usual multi-day bushwalking gear.
Disadvantages: Water takes time and fuel to treat, and time to cool down enough to drink or decant to other containers. Hard to do efficiently in large quantities quickly. Extra fuel is needed.

Chemical How to use chemicals to treat water

Chemical treatments are effective against viruses, bacteria, protozoa. Examples of chemical treatments include

Iodine denatures proteins in any living matter. 2% formulation five drops per litre, ten drops per litre if cloudy. Allow to stand for 30 minutes before drinking.

Advantages: Likely to be already carrying this in your first aid kit. Lightweight.
Disadvantages: takes time to be effective. Unpleasant chemical taste, potential adverse health effects if used for prolonged periods.

Chlorine Dioxide products sterilizes water by disrupting critical processes by living matter. Micropure tablets – use one tablet for 1 litre of water and take 30 minutes for bacteria and viruses, 2 hours for Giardia in clear water. Aquamira drops require two solutions to be mixed and take 15 minutes to treat water.

Advantages: Generally accepted to be more effective than iodine, better tasting and better for health. Lightweight.
Disadvantages: Must be careful to pack the tablets so that they don’t get crushed. Takes time for water to be safe to drink (30 minutes – 2 hours). May have to pre-filter water if organic substances are present because they will inactivate many chemical treatments.

Radiation (UV) How to use radiation (UV) to treat water

Radiation treatment is effective against viruses, bacteria and protozoa. UV light sterilizes water by damaging the nucleic acids of pathogens that are involved in reproduction. Cellular RNA and DNA absorb UV energy, which breaks necessary bonds in these molecules. Without the ability to reproduce the pathogens cannot spread and infect. So UV light do not kill or remove pathogens, but rather de-activates them.

The steripen can sterilise 0.5 L water in a minute. It is generally most effective against bacteria and viruses, and less so against Protozoa because of their thicker cell wall. The water source is preferably as clear as possible because any organic matter in the water reduces the effectiveness of the UV treatment by absorbing UV light. Users must remember to recharge for every trip, and carry spare batteries for extended trips.

Advantages: Water immediately ready to drink; doesn’t taste funny.
Disadvantage: Need to carry backup water purification methods in case of machine failure or batteries running out in the field.

Filtration How to use filtration

Filtration can be used to remove macroparticles using cloth fabric or microparticles using specialised pumps.

1 Macro-filter using fabric
Most simply, fabric-filtering removes large sediments include floating leaves, sticks, mud and other debris, but no harmful pathogens. Water can be effectively filtered through a clean t-shirt, handkerchief, bandana, coffee filter paper or a commercial pre-filter.

Advantage: no specialised equipment required other than clothes!
Disadvantage: doesn’t remove harmful pathogens

2 Microfilter using a pump
Microfilter pumps remove bacteria, protozoa, cysts and sediments, and sometimes but not always viruses. In general, water is pumped through pores of 0.2-0.3 µm diameter depending on the model, leaving bacteria, protozoa, cysts and sediments behind. The Katadyn Hiker Pro does 1 L/min. Filters and cartridges may need regular replacement depending on how dirty the water is.

Advantage: Water is ready very quickly (the “Katadyn Hiker Pro” does 1 L/minute).
Disadvantages: Need to carry backup water purification methods in case pump breaks in the field; does not necessarily remove viruses. Technical support from Katadyn says:
“Due to their tiny size, viruses can theoretically not be removed with a 0.2 micron (or any physical) filter. Nevertheless, long-term experience in the field has indicated that Katadyn Filters can retain viruses. This surprising fact can be explained: Viruses have an electrical surface charge that attaches them to other particles or materials. Therefore, the tight pore structure of the Katadyn Filters removes the viruses attached to particles from your drinking water.”

3. Microfilter by sucking
A much cheaper form of filtration is the LifeStraw, where the user sucks clean water through a filter before drinking. This method removes bacteria, protozoa, cysts and sediments, but not microscopic minerals, chemicals and viruses. Water is pumped through pores (0.2-0.3 µm diameter depending on model) leaving bacteria, protozoa, cysts and sediments behind. This lasts for 1000 litres (approximately a year of drinking water).

Advantages: Water immediately drinkable. Filter lasts for approximately a year.
Disadvantages: Doesn’t remove microscopic minerals, chemicals, or viruses. Only can be used by one person at a time. Short straw length means that you need to be at the water source to drink. That is, clean water cannot be carried to camp. Alternatively, stick it into a wide-brimmed water bottle, but this can be fiddly. An alternative is the Sawyer bottle.

Desal How to make salt water drinkable

While humans cannot drink salt water straight, it’s possible to use a de-sal unit to make the water palatable.

Portable reverse osmosis units are available and can be used in emergency situations. They work by manually pumping water through a semipermeable membrane that removes enough salt to make it palatable. The size of the pores are so small that extremely pure drinking water is produced, but the process is slow. Katadyn claims to have the world’s smallest desal unit called the Survivor 06, which produces 0.89 litres of water per hour at a pumping frequency of 40 pumps per minute. While this is achievable in an emergency situation, it’s not that practical on a multi-day coastal bushwalk.

Water Management

Management strategies you can use to look after your water supplies

I want to be like water. I want to slip through fingers, but hold up a ship. Michelle Williams

Managing an upset stomach in the bush
An upset stomach is unpleasant at the best of times, particularly on a bushwalk. They’re relatively uncommon, however, being prepared with a handy trowel, plenty of toilet paper, antibacterial gel and baby wipes can make stomach upsets easier to manage in the field.

If possible, after a stomach upset, lie low for a day or two at a base camp. Adding gastrolyte tablets to water can be a good way of rehydrating, as bouts of diarrhoea or vomiting mean significant water losses.

Once back home, if symptoms persist, seek medical attention, where stool samples can be used to test for infection and treatment can be given.

Managing water containers
Having a well-organised water container system avoids mix-ups between treated and untreated water, particularly when the treatment process can take time to be effective, such as chemical.

There are a few options:

  • Colour coded or labelled bottles to easily identify treated from untreated water. This works well for treatments that take time.
  • A large source bladder with untreated water that is decanted into drinking bottles as it is treated. This works well for UV treatments or filtration treatments.

Stomaching distasteful water
Nasty tasting water can be unpleasant to drink but unavoidable in some scenarios. Sometimes water sources are heavy with tannins or have relatively high salt content, such as bore water. In these cases, the water is less palatable than water people are generally used to, and some people can find it hard to drink.

A few ways to solve this.
On the track:

    • Add light cordial powders or sugar
    • Set drinking goals by measuring the amount of water consumed. This can reduce the risk of dehydration
    • Filtering using a pump can remove sediment, tannins, heavy metals and bad taste.

At camp:

Backup treatment options
People generally develop a favourite way of treating water, and that’s what they carry. But it’s sensible to carry some backup in case things go wrong. Anything relying on a battery can run out. Tablets can get lost or waterlogged. Make sure there are some backups in the group, especially when walking in areas with lots of campers or downstream from houses, farms or industrial dwellings.

Foot Maintenance

How to have healthy feet

Your feet will bring you to where your heart it. Irish proverb
Your feet will bring you to where your heart it. Irish proverb


A successful bushwalk means not only looking after your feet on the track but also taking good care of your feet back home. A regular foot care routine will minimise foot problems in the bush, and when done over a lifetime, makes for an enjoyable long-lasting bushwalking career.

Foot care can be broken down into three parts – at home, on a bushwalk and other related matters.

At Home How to look after feet at home


  • Check feet daily: Feet swell during the day, so inspect feet after they’ve been in shoes for several hours. Look for small cuts, bruises, scrapes, swelling, toenail infections or other skin abrasions and monitor.
  • Wash feet regularly: Wash with warm soapy water including between toes. Dry with a towel and use talcum powder to keep a dry environment between toes and prevent infection.
  • Keep toenails trimmed: Cut nails after showering or swimming when the nails are soft. Use nail clippers or scissors to keep nails short. Cut directly across the top of the nail, and smooth rough edges with a nail file (this prevents ingrown toenails).
  • Monitor corns and callouses: Thick patches of skin can form on the soles of the feet. Podiatrist advice may be needed to obtain a suitable treatment.

On a Bushwalk How to look after feet on the track


  • Use appropriate footwear: Select shoes or boots that fit well and are suitable for the terrain and temperature conditions. Use sunscreen if wearing thongs or sandals, and warm footwear in cold conditions.
  • Use appropriate socks: Wear comfortable socks that help keep feet dry. Avoid cotton as it holds moisture and increases friction.
  • Fix problems as soon as they’re noticed: Remove stones or sharp objects immediately. Skin abrasion rapidly becomes uncomfortable and can lead to infection. Treat blisters early. Try adjusting lacing if footwear becomes uncomfortable.
  • Air and check feet at rest stops: Take off footwear and allow feet to dry at rest stops. Shake out any stones, rocks, sand or sticks. Do a quick check for any ticks or leeches that may have gone unnoticed and treat appropriately. On overnight or longer walks, consider resting and washing feet in creeks (downstream from any drinking water collection points) to relieve swelling or tension. Removing boots and elevating feet can also reduce swelling. On overnight walks, air out feet at camp by wearing sandals or thongs, and treat any issues (e.g. skin abrasions).
  • Take a change of socks: It’s hard to avoid socks getting saturated with sweat and this moisture build up can increase the chance of blisters, odor and infection. Some people find that changing socks half way through a day walk can be an effective way of keeping feet dry and avoiding blisters. On overnight or longer trips, carry enough socks so that while some are drying, others are dry enough to wear.
  • Dry feet after river crossings: Some bushwalks require wading across rivers or streams. Take a spare pair of sandals for river crossings and dry feet thoroughly before putting on walking footwear.

Other Tips Other tips to keep feet strong and healthy for life


  • Strengthening exercises: Basic strengthening of the feet, calves and Achilles can make a big difference to reducing foot pain or strain on a bushwalk.
  • Lightweight gear: Carrying a heavy pack increases the chance of foot injuries. The extra weight invariably leads to earlier and deeper fatigue and mistakes such as tripping or slipping. Consider lighter gear and/or sharing group items (e.g. tent, stove).
  • Gaiters: Use gaiters to stop stones, sand and vegetation getting into footwear, and to reduce the chance of a snake bite penetrating.
  • Reduce foot odour: Foot odour is caused by the bacteria built up. Feet have a lot of sweat glands, and some people are very prone to sweating even without much exercise. Wash feet regularly and thoroughly. Clean well between toes and edges of toenails where bacteria can build up. Dry feet thoroughly and use talcum powder to keep a dry environment between toes. Wear wicking socks to keep feet dry. If particularly odour prone, consider using an antiperspirant, and after the walk, thoroughly air footwear, and sprinkle baking soda or talcum powder onto the insoles to reduce odor. Alternatively, try some home remedies for treating smelly feet.
  • Use high-quality insoles: Some cheaper footwear has poor quality foam insoles that quickly wear thin, reducing support and shock absorption. High-quality replacements such as Montrail Enduro-Soles can make all the difference and may even outlast the shoes or boots.


Foot care gear


Below are some ideas for gear items that may help deal with foot problems arising on a bushwalk (most commonly, blisters): be prepared to experiment with a range of products to find out what works best. Also, visit Rebecca Rushton’s website for ideas on essential items for a blister prevention kit.

Antiseptic cream/liquid: Betadine is better as a liquid, because it soaks down the side of the nail and under broken skin, whereas cream tends just to sit on the top. Cream is good for a deroofed blister (because it gets full contact with the wound base), though liquid works just as good. The liquid comes in a small 15 ml eyedropper bottle which is great for low bulk.

Island dressings: Absorbent pads with adhesive backing around the perimeter allowing the pad to be secured to the skin without putting adhesive directly on the wound. Excellent for protecting intact or broken blisters.

Compeed hydrocolloid dressings: Dressings with gel-forming agents that adhere to the skin around the wound but not the wound itself. These are for dressing deroofed blisters only, not blisters with an intact roof or torn roof. See

Penknife: Penknife, with scissors for cutting nails.

Tape: Some people find taping up the blister-prone areas before starting the walk can be an effective way of preventing blisters. Fixomull is commonly used and preferable to Elastoplast because it sticks better (even in sweaty and moist conditions) and there is less risk of sensitivity. Experiment with different types of tape to see what tapes work best, then refine the application technique. Careless taping where the tape comes off, bunches, or doesn’t cover the right place, may lead to blisters.

Moisturiser: Relief for dry or cracked skin.

Scalpel blade – a lance is preferable to pins or needles for lancing blisters as a pin-hole quickly closes and fluid can build up. Safety pins are good for removing splinters or attaching wet socks to the pack when drying.


How to prevent and treat blisters

If ignorance were bliss,
he’d be a blister. Blaise Pascal

Foot blisters make walking extremely uncomfortable and can turn a fun bushwalk into something miserable, however, with good management, blisters can be prevented. It’s a matter of getting the right fitting footwear and having a good foot care routine. The basics are covered below, but check out Rebecca Rushton’s site for more.

How blisters form What causes blisters to form on the skin

Most people think that blisters form from friction and rubbing directly on the skin surface, but in fact, blisters are caused by the skin stretching too much. So it’s a shearing force rather than a rubbing one.

When skin is repeatedly stretched too far, tiny tears form underneath the skin surface, and this is the start of a blister. The area starts to fill with fluid in an attempt to repair and protect the area, but if the rubbing continues the skin gets damaged, the blister bursts and the skin is open to infection causing the bushwalker mild to severe discomfort (depending on where the blister is located).

Shear forces are different to rubbing forces because they occur beneath the skin.

Rebecca Rushton has an elegant example of what skin shear feels like:
“Place the tip of your right index finger on the back of your left hand. Wobble it back and forth but keep it stuck to the same bit of skin. Notice how your skin stretches? This is shear and this is what causes blisters.”

Skin is made up of several layers, similar to several layers of plastic. A shear force occurs when the layers move in different directions (or at different speeds). If the shear force is big enough then it will break the joins between the skin. The blister then forms as the body repairs the area by pumping fluid into the injured area, and since there is no material holding the layers together the skin balloons out.

On a bushwalk, feet are usually held tightly in place in footwear by frictional forces between the skin, sock and shoe and lacing. When walking, on every step that contacts the ground, the outer skin of the foot sticks but the other layers move. This creates a shear force on the skin and if the skin is repeatedly stretched further than its natural elasticity, blisters form.

So to reduce blisters we need to reduce shear forces within the skin. Some people are more susceptible to blisters than others. Rebecca Rushton suggests there are four requirements:

  1. Skin resilience: everyone has a different level of shear strength in their skin and it varies across the body depending on skin thickness. In general, thicker skin is more likely to form blisters because it’s less mobile, and that’s why blisters tend to form on feet where the skin tends to be thicker.
  2. A high friction microclimate: in a sweaty shoe heat and moisture increase friction in an already high friction environment. If this friction can be reduced, so are the shear forces and the likelihood of getting blisters. Therefore, using techniques to reduce friction is crucial to avoiding blisters.
  3. Internal structure: the further the inner layers of skin move relative to the outer skin the more likely blisters are to form. Foot bones move quite a lot under the skin. Changing the biomechanics – the structure and function of the body – can lead to immediate blister prevention. These are some of the factors that vary from person to person.
  4. How often blisters form: repetitions are how many steps you take. Each step imparts a shear distortion to the skin, so the more steps, the more likely shear damage occurs. Hence, the longer your walk, the more likely you are to be troubled with blisters. Also relevant to this point – the heavier your pack, the more challenging the terrain etc, the sooner the skin integrity will fail, leading to blister formation.

Blisters prevention How to prevent blisters from forming

There are a variety of different techniques that can be used to tackle blisters. Each have their pros and cons. Try a variety of techniques to find out what works best.

The right footwear
The most straightforward way of preventing blisters is to make sure that footwear fits well. Well-fitting footwear will be most comfortable and enjoyable to walk in. Minor adjustments to a shoe fit can be made using different lacing techniques. However, some people with well-fitting shoes can still be susceptible to blisters.

Walking in wet footwear increases friction between the shoe and the skin, making walkers far more blister prone. Carry a separate pair of sandals for river crossings and make sure to dry your feet well before putting walking footwear back on.

The right socks
It’s not friction between the skin and the shoe that causes blisters, but rather the rubbing between the various layers of skin (i.e. shearing forces between skin layers). This occurs when there is high friction between the skin and sock. Reducing this friction reduces the shear forces between skin layers.

Moisture on the skin increases friction on the skin. Standard socks absorb some moisture to prevent this, but when exercising, they become saturated quickly. Socks that wick moisture away from the skin may help prevent blisters. Moisture evaporates through the footwear surface until the sock material is saturated, and then the limiting factor is how fast moisture can escape from the footwear. Sometimes this is very slow. Cotton is considered to be the worst material for endurance activity clothing because it keeps moisture trapped against the skin – just the environment for blisters. Acrylic and polyester are effective wicking materials and dry quickly.

Some people find that using two layers of socks are an effective way of reducing the friction between sock and skin, however, the sort of materials and wicking properties are important to get right here. In some cases, using a single sock layer is more effective.
You might find moisture-wicking socks, double-socks or toe-socks help you prevent blisters.

Reducing friction
As well as good socks and removing moisture from the skin, there are other ways to reduce friction. Some of these methods include:

  • Tape: taping up the blister-prone area before starting the walk can be an effective way of preventing blisters for some people, although it’s a time-consuming process, with variable results.
  • ENGO Blister Prevention Patches are made of Polytetrafluoroethylene (PTFE), an ultra-low friction material. They are applied to the insole of the shoe to reduce friction in common blister-prone areas. They’re fast to apply and long lasting but don’t work well when waterlogged.
  • Lubricants: care should be taken using lubricants, as research has found that greasy lubricants don’t last long (60-90 minutes), while others actually increase friction. Use with caution!

Blister treatment How to treat a blister on a bushwalk

New footwear or socks take some time to get used to, and blisters may form during the breaking in process. Alternatively, maybe something happened on the trip that was different – a river crossing and wetter feet than normal. Hotspots are the first warning signs of a blister forming. They’re much easier to treat than full blisters, but if ignored will turn into a blister.

Here are some strategies on how to recognise and deal with hotspots and blisters in the bush.

Hotspots Recognising and treating hotspots

Hotspots are red sores that appear on the skin in an area which has been or is being irritated and are often the first warning sign of an impending blister. That is, there’s still time to prevent it. Stop and take the time to sort it out before it gets any worse. It’s tempting just to push on, but a short stop and a quick fix will most likely prevent a blister forming.

Apply blister prevention strategies. On a bushwalk, the easiest ways to treat hotspots include: taping with Fixomull, Elastoplast or Moleskin.

Treating blisters Treating blisters in the bush

The best way to treat a blister depends on how much of the blister roof is still intact. The roof is defined as the top of the blister, and could be intact, torn or deroofed, meaning that the upper skin is complete, partially broken or completely missing. Broken skin makes the skin more prone to infection, and given that feet are in a moist warm environment, they are more prone to infection.

The aim of blister treatment is to stop them happening, and if they occur, avoid infection, reduce pain, and speed up healing.

Intact blisters are prone to popping once footwear is put on again, so they need to be dressed carefully to reduce the risk of future tearing. Because it is likely to tear skin when removed, don’t put anything sticky on the blister. Use an island dressing, which has strong adhesive on the outside of the bandage and gauze in the middle. Reduce friction, and pressure on the area (e.g. if possible, use different lacing techniques to reduce pressure around the blister) and monitor in case the blister roof tears.

Lancing a blister is to prick or cut open. Whether or not to lance depends on where the blister is located, what the activity is, the health of the patient and what equipment is available. In theory, bushwalkers cannot keep a wound clean enough to justify lancing the blister in the field. However, in practice, many bushwalkers find that with appropriate antiseptic and dressing that the blister does not get infected. Moral of the story: lance with caution and use an antiseptic when the fluid is drained.

A blister with a broken roof is prone to infection, and first aid treatment must be given to reduce the chance of infection. Put antiseptic on the wound (e.g. Betadine) and follow the same steps as for unbroken blisters and monitor for infection.

When the entire roof of the blister is missing, the wound is prone to infection and the underlying skin needs protection as it is delicate and sensitive. The skin will also weep, so the wound should be protected with a hydrocolloid dressing, which allows healing skin without sticking to it. Follow the same steps as for broken blisters, with a hydrocolloid dressing (e.g. Compeed) instead.

Foot Infections

How to avoid food illnesses and infections

We are all connected.
When one arm of foot is poisoned,
the whole body becomes infected. Suzy Kassem

Skin provides a natural barrier, but if that barrier gets broke via a wound, then the area is prone to infection. Due to the warm moist environment surrounding feet, bacterial and fungal infections are common. People with medical complications such as diabetes often have poor circulation, and are most susceptible to foot infections. If an infection doesn’t clear up quickly or gets worse, seek medical attention.

Bacterial infections
Typical signs of bacterial infection include:

  • Increased redness, swelling, pain, warmth and tenderness around the area.
  • Pus in and around the area.
  • Fever.

This inflammatory response is the body’s way of protecting against infection. The immune system is kicked into action. In an attempt to fight off the infection, extra blood is sent to the affected area and that’s what causes the localised redness, swelling and warmth. Inflammatory responses may also occur in areas of the body that are overused or have minor injuries, and are not necessarily associated with infection.

Infected areas can turn nasty pretty quickly, particularly in hot and humid conditions – perfect for pathogens to multiply. Unfortunately, those are the exact conditions that feet are subject to in sweaty socks and shoes, so wounds on feet are particularly susceptible to infection. On bushwalks it’s important to take precautions to prevent any injuries or wounds getting infected, and to seek medical attention if the patient’s condition deteriorates.

While it’s impossible to dodge small wounds and cuts entirely, good foot care and maintenance can go a long way to reducing the chance of infection. Appropriate management of infections in the field is important.


  • In the field: If skin is broken, clean the area with a saline solution or alcohol wipes or just water if nothing else is available. Apply antiseptic cream (e.g. betadine) and put on suitable bandage depending on size and location of the wound. Monitor the patient for signs of infection such as increased aches, pain and fever. If the condition becomes serious, seek medical attention.
  • At home: regularly clean and dress the wound. Monitor and seek medical attention if the wound does not heal.

Yeast infections
Because shoes provide the ideal warm, moist conditions for fungi to thrive, feet are also extremely susceptible to fungal infections.

Common fungal infections include:

  • Athlete’s foot – Symptoms: red, itchy patches. White flaking skin.
  • Jock itch – Symptoms: rash, patches of redness or bumps.
  • Ringworm – Symptoms: itchy, red, scaly patches.

Athlete’s foot, jock itch and ringworm are all caused by dermatophyte fungi, although athlete’s foot can occasionally triggered by yeast (candida) infections. Fungi feed on keratin, which is a protein found in skin, hair and nails.

There are some simple steps to follow to reduce the chance of getting a fungal infection:

  • Develop a good foot maintenance routine.
  • Wear footwear and socks made from breathable materials.
  • Wash feet thoroughly after exercise and change socks.
  • Keep toenails cut short and clean them regularly (note that fungal infections can develop underneath toenails).
  • Air feet out as much as possible (i.e. use open shoes around the house). When feet are infected, avoid walking barefoot as this can spread fungal infection.


  • In the field: Because it’s hard to properly keep the feet clean and dry on a bushwalk, fungal infections are difficult to eradicate. Consider soaking feet in creeks (downstream from any water collection points) for relief, applying antifungal cream (if this is something in the first aid kit) and changing socks regularly to keep feet as dry as possible.
  • At home: wash and dry the rash area thoroughly; apply antifungal creams and/or powders; seek medical attention if it hasn’t cleared up within two weeks or gets worse.

Foot Pain

How to prevent and deal with foot pain on a bushwalk

When our feet hurt,
we hurt all over. Socrates

Foot pain is most likely caused by injury, disease, trauma, some biomechanical misalignment or a poor choice of footwear. Walking and weight bearing for extended periods in poorly fitting footwear or on an injured/inflamed foot leads to pain and tenderness, with the potential for long-term problems.

Below are some common foot complaints with short- and long-term treatments in the bush and at home, and prevention methods.
Important: If foot pain persists, seek medical attention. Some of these conditions must be treated effectively early on to prevent long-term problems.

Heel Pain
Heel pain refers to the extreme discomfort felt through any part of the heel. It can be caused by:

  1. Overuse: Repeated impact on a specific part of the foot.
  2. Plantar fasciitis: Inflammation of the tissue that runs along the bottom of the foot connecting the heel with the toes. This is often a result of a biomechanical problem such as flat feet.

Try a heel cup or cradle, heel or an orthotic to absorb shock. Select footwear that has good arch support and heel height.


  1. In the field: Take frequent rests; consider shortening the trip; seek medical attention if pain gets worse.
  2. Back home: Rest and recover until pain subsides, reduce physical activity.

Achilles tendonitis
The Achilles tendon inserts into the heel from the back of the leg and controls flexing movements of the foot. Achilles tendonitis is the inflammation of the Achilles tendon, resulting in a sharp shooting burning pain and should be treated to prevent complications.

Achilles Tendonitis can be caused by:

  1. Over-pronation: The arch of the foot collapses under weight-bearing and the foot tends to tilt inwards on a flat surface
  2. Poor footwear fitting
  3. Short Achilles tendon
  4. Trauma to Achilles tendon
  5. Inadequate stretching and strengthening before an activity

Stretch well before heading out on a walk to warm up the muscles. Try a heel cup or cradle, heel or appropriate orthotic to control for over-pronation and support the longitudinal arch.


  1. In the field: Take frequent rests; consider shortening the trip; seek medical attention if pain gets worse.
  2. Back home: Rest and recover until pain subsides, reduce physical activity. Apply ice afterwards and avoid walks with steep uphill climbs.

Arch Pain/Strain
Arch pain can be the result of inflammation or burning of muscles associated with the arch of the foot.
Arch pain/strain can be caused by:

  1. Foot injury or structural imbalance
  2. Plantar fasciitis: Inflammation of the tissue that runs along the bottom of the foot connecting heel with toes. Often a result of some biomechanical problem such as flat feet.

Use well-fitting footwear with good shock-absorbing soles. Consider an orthotic to give good arch support and prevent overpronation.


  • In the field: Take frequent rests; consider shortening the trip; seek medical attention if pain gets worse.
  • At home: Very important to treat this condition before it worsens. Rest and recover until pain subsides, reduce physical activity. Avoid shoes with heels.

Bunions are a prominent bump on the inside of the foot beside the joint of the big toe. They’re a common foot problem caused by the big toe bone moving towards the smaller toes and it’s possible that the big toe rests above or below the second toe. Bunions may cause swelling, inflammation and soreness and in extreme cases may cause walking difficulties. The analogous problem (a Bunionette) may also occur on the outside of the foot at the little toe joint due to the little toe moving inwards towards the fourth toe.

Bunions are more common in women and are thought to be associated with wearing dress shoes that are too small for the toes. Select shoes with a wide toebox.

At home: Bathing feet in warm water; wearing properly fitting shoes preferably with a wide toebox; orthotics for additional support, comfort and protection. Some people find bunion shield effective at reducing pain and limiting bunion formation.

Sun Exposure

Why you need to be careful in the sun

Overexposure to the sun often leads to sunburn, with the skin becoming reddened and inflamed. In extreme cases, blistering and peeling occur, and this has been linked to a higher risk of skin cancer.

The sun produces visible light and other types of electromagnetic radiation that are invisible to the human eye.

Visible light consists of wavelengths in the range of 400-700 nanometers. Ultraviolet (UV) light is a shorter wavelength, higher frequency light that literally translates to ‘beyond blue’, and is in the blue end of the colour spectrum. UV ranges from 200-400 nanometers and is further broken down into three categories: UVA (320-400nm), UVB (290-320nm) and UVC (200-290nm).

UV has different properties to visible light. For instance, if a cloud blocks a percentage of visible light on a cloudy day, it will not block the same percentage of UV. Similarly, UVA, UVB and UVC have different behavioural properties such as scattering and absorption. The earth’s atmosphere blocks most of the lower wavelength UV (almost all of UVC and most of UVB), so that on most of the UV that reaches the earth is UVA (~95%), the longest wavelength UV. Because thick clouds block UVB, the amount of UVB that makes it to the earth’s surface is heavily dependent on cloud cover.

UVB induces production of Vitamin D, which is vital for bone health, the nervous system, the immune system and controlling insulin secretion. But, overexposure to UVB can have acute and harmful effects. UVB causes direct damage to DNA, which can lead to replication mutations and eventually cancer. By contrast, UVA causes indirect damage to DNA via free radicals, and this indirect damage can lead to cancer[note]De Gruijl, F.R., [33] Photocarcinogenesis: UVA vs UVB, in Methods in Enzymology. 2000, Academic Press. p. 359-366[/note]. While UVA appears to be less carcinogenic than UVB, it is more abundant in sunlight than UVB. Hence UVA contributes significantly to the carcinogenicity of sunlight.

Melanin is the body’s defence against UV. Upon exposure to UV, the brown skin pigment increases – suntan. Melanin can absorb and disperse UV to some degree to protect the body’s precious DNA. In general, people with darker skin are more likely to withstand greater sun exposure than fair-skinned people.

Most sunburn appears to happen near the boundary of the UVA and UVB bands. This has led to the development of the ultraviolet index or UV Index, an international standard that conveys information about the strength of UV at a given location and time, and can be found for Australia on the Bureau of Meteorology website.


Modified from World Health Organization, and International Commission on Non-Ionizing Radiation Protection. Global solar UV index: a practical guide. (2002)

Due to the thinning of the ozone layer in the mid-latitude parts of the earth, Australia has a high UV risk. Without the ozone layer to stop the sun’s powerful radiation, UV can penetrate to the earth’s surface, including through clouds. So even on a cloudy day, it’s possible to get burnt. In most parts of Australia, the UV index is high-extremely high all year around, so it’s sensible to use sun protection all year. If in doubt, check the UV index forecast before heading out.

Reflected UV can be as dangerous as direct UV. Shiny surfaces such as water and snow reflect UV and can catch bushwalkers unexpectedly, particularly if the air temperature is cool and keeping warm is more to mind rather than sunbathing. Similarly, sun exposure is a problem at high elevations because UV exposure increases with altitude. Sun exposure is also a issue in countries where the malarial medication doxycycline is taken – it makes the skin more sensitive to sunburn.

Hence, sun protection may be as important in winter as it is in summer: use a hat, sunglasses, sunscreen, and a good shirt all year round.