Safe drinking water

All bushwalkers and ski tourers require safe drinking water, whether carried, collected from a pool, stream or river, or obtained from a tank or water drop. Illness caused by contaminated water will spoil the trip.

It is not possible to determine just by looking at a clear body of water that it is safe to drink. If livestock, wildlife and other people can reach a location so too can contaminants. As more walkers and skiers venture into wilderness areas, the potential for contamination rises. If in any doubt it is best to treat water from any source.

Poor hygiene causes illness that is often attributed to contaminated water. Water treatment options are ineffective if basic hand hygiene is not observed, so wash hands well or use hand sanitizer after toileting and before water collection and food preparation.

Minimum water requirements

Minimum daily water requirement in cool conditions is around 2.5 – 3 litres per person, which rises to two or three times this amount in hot conditions, or when undertaking strenuous activity. Most bushwalkers will consume around 3–4 litres per person for a ‘dry’ overnight camp. Have plenty to drink, as dehydration is a common problem.

When planning a trip, consider:

  • Water weighs 1 kg per litre so it is prohibitively heavy to carry any substantial quantity. Hence, there is a need on most overnight trips to get safe drinking water along the way. 
  • Some available water sources may be unsuitable for drinking without treatment.
  • Some bushwalks have tank water available – check with land managers about this.
  • Putting in water drops ahead of the trip to make a particular trip feasible.  When the trip is over, all water drums must be collected.

Note: The effects of climate change have made some once reliable water sources for bushwalkers unreliable.

Water collection

When collecting water, look for:

  • Flowing water as it’s less likely to harbour pathogens
  • Calm water in a lake or pool has less sediment and is easier to filter and purify
  • Clean packed snow. Icy snow contains more water than the equivalent volume of fresh  snow. When collecting snow for water, ensure some water remains in the bottle to aid thawing.


  • Areas of animal activity – e.g. faeces, ground disturbance, animal tracks, etc.
  • Areas polluted by people
  • Collecting water downstream of huts and campsites
  • Sedimented or brackish water, foam or brown scum
  • Discoloured snow

Collect water from the surface of pools and away from the edge. Some contaminants, such as giardia cysts, are heavy and sink and pathogens can occur in larger numbers along a lake shore or river bank.

After heavy rain, wait before collecting water as runoff increases bacterial loads and muddies the water making filtering more difficult.

Types of water contamination

There is a wide variety of water contaminants. The dangers posed by and best methods of treating them vary significantly. The following are some of the main contamination types.

Dissolved natural materials

  • Salty or brackish water is unpleasant to drink.
  • Very salty water is unsuitable for drinking and as it is not possible to remove salt with a portable device.
  • The only practical options are to follow a watercourse upstream until past the tidal zone or to look for a freshwater spring.
  • Slightly brackish water can be made more palatable with powdered drink flavourings.
  • Some water sources contain tannin from vegetation, giving water a brown colour.  Tannin is harmless but it may taste strange.
  • Bore water for stock (e.g. as found in the Flinders Ranges) may have a high mineral content that makes it unsuitable for drinking by humans.

Suspended natural materials

Suspended natural materials include soil and clay, vegetable matter and algal growths. Excluding algal growths, the threat posed by these contaminants is low. 

Blue-green algae

Blue-green algae is toxic in high concentrations. Algal contamination can be detected by its appearance (turgid, thick, coloured water) and smell (earthy, pungent, musty, septic).

Some slow flowing rivers are susceptible to major algal blooms, particularly if there is nutrient runoff from agricultural land and during droughts. All coloured algal blooms must be treated as potentially toxic.

Water filters cannot be relied on to remove blue-green algae toxins.


The following pathogens can cause problems for bushwalkers:

  • Giardia is endemic in some streams and lakes. Symptoms include diarrhoea and flatulence and can occur 10–14 days after contamination. If infection is suspected, visit a doctor.
  • Cryptosporidium is spread by contamination of water sources with toilet waste, producing similar symptoms to Giardia
  • E. coli can produce diarrhoea, vomiting and other stomach symptoms and is a significant threat to health. E. coli contamination is common near high-use huts, near ski resorts and in bushwalking areas where runoff from urban areas enters bushland, e.g. in the Blue Mountains, New South Wales.
  • Viruses (e.g. hepatitis A, rotavirus, norovirus) are too small for filters to effectively 

See Water treatment options for information on dealing with contaminated water.

References and external links