OK, so you’ve got your next bushwalking trip organised, you’ve decided on the route, got your food dehydrated and meals planned, gear lists done and your backpack is going to be full as a goog. Now you need to consider what you’re going to do about drinking water. This will be determined by a number of factors.

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litres for a day’s walking in a temperate environment. Cooking may require more. If it’s hot and exposed and you’re in tough terrain you’d need to increase this amount. If it’s a wetter environment with plenty of water refill spots then you can carry a lot less - maybe only a couple of 600 ml plastic containers.

Remember every one litre of water is an additional one kilogram of weight - and for the lightweight walk-ers out there - there is no way to dehydrate water!

What will you carry your water in?

Hydration packs are a bladder that is situated inside the pack against your back behind the harness system (or hang between the mesh back and your back as in the new Macpac Tasman 45 ) - and are typically two – three litres capacity. They have a rub-bery tubing and a mouth-piece which means you can access water in small amounts by sipping as you go along. It may be hard to assess how much water you drink (and therefore require for a trip) with this method.

Traditionally water has been carried in metal Sigg type bottles, or wide mouthed plastic Nalgene type bot-tles, but these tend to be bulky and heavy, and when empty, can’t be compressed down. These days it’s often good to carry the water in the clear collapsible plastic containers such as those made by Platypus and Evernew (this latter brand needs to be sourced from overseas though). They have a lot of sizes rang-ing from 600 ml up to several litres. You can visualise the water, they are light, and they collapse down well when small. Recycled bottled water containers and wider mouthed Gatorade type bottles are popular - light, cheap, replaceable. Some others like to carry larger amounts in wine cask bladders (I’d worry they may burst!)

How will you make your water suitable to drink?

I’ll go into a bit more detail here. Firstly, what nas-ties do we need to worry about that are in water?How do we deal with these?

Some things in water are physical or dissolved substances.

Floating leaves, sticks, mud etc will need to be grossly filtered out by passing the water through a handkerchief or bandanna or coffee filter paper or a commercial prefilter such as those made by Steripen. Tannins are the dissolved products from timber that turn the water brown and give it a strong taste. Some water may have a higher mineral content with dis-solved salts that may change the taste, like brackish water. Fertilisers may be present in water from farm runoff. Water may be contaminated from heavy metals from mining activity. Some water purification methods don’t remove these, those with activated charcoal filters may remove some.

Living contaminants are the ones we’re often concerned about avoiding. They will most commonly cause problems such as diarrhoea, but can also affect other organs such as the liver. Many trips have been spoiled by a funny tummy.

• Viruses such as rotavirus and hepatitis. These are very small and some filters may not remove them.• Bacteria such as E.Coli, cholera and salmonella are found in the gastrointestinal tract of people and animals and are a common contaminant. They can cause diarrhoea and dysentry, and also systemic (body-wide) effects in some cases. Boiling filtering and chlorine will deal with them.• Protozoa such as Giardia and Cryptosporidia are enteric organisms of people and animals that have a complex lifecycle, cause diarrhoea and can be difficult to eliminate from the body.• Nematodes such as schistosomes can not only enter your body via drinking water, but also via skin penetration eg by swimming, these are more of a problem overseas in places like Africa and Asia.

WATER TREATMENT METHODS:

Boiling, chemical inactivation, filtering and ultravio-let (UV) sterilisation are the main methods I’ll outline. E coli and giardia are the most common ‘bugs’ we tend to worry about

Boiling

Boiling has long been used to make water safe to drink. Boiled water does, however, make the water taste ‘flat’ afterwards, and some people may like to add something like Staminade or Tang or Gatorade

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powder afterwards. It’s cheap and easy and kills both E coli and giardia.

Boiling - you need to have a rolling boil for one minute, and three minutes if above 2000 metre altitude. The longer time is needed because the boiling point is diminished below 100 degrees Celsius the higher the altitude.

Chemical Inactivation

NB dirty water will need to be filtered first by some method, as organic substances present in water will inactivate many chemical treatments.

Household bleachUsually 6% sodium hypochloriteUse the plain stuff, not lemon scented or whatever!2 drops per litre water (the yanks use 1/4 table spoon per gallon)4 drops if cloudyAllow to stand 30 minutes before drinkingNB 20 drops = 1 ml, therefore 1 drop = 0.05 ml (Ask your friendly local veterinarian for a 1 ml syringe)

Tincture of Iodine

Often carried in a first aid kit as a disinfectant for wounds2% formulation5 drops per litre10 drops per litre if cloudyAllow to stand for 30 minutes before drinking

Also available are Coghlan’s iodine tablets.

Kills giardia more readily than crypto. Will kill E coli. Disadvantage - horrible smell!

Chlorine dioxide tablets

Eg, Katadyn Micropur tabletsare effective against viruses, bacteria (30 minutes), but less effective against crypto and giardia (2 hours).Good as they are small and light, may leave a smell and taste though. Main disadvan-tage is the time delay between treating and drinking.

Aquamira drops

Made by McNett. More widely available overseas, but some shops in Australia now stock them.These have become popular recently due to them being small and easily pack-able. Negligible smell and taste. You can also decant a

small amount out to take with you as needed.They are a stabilised form of chlorine dioxide in bottle A and an activator in bottle B. You mix seven drops of part A with seven drops of part B. Wait five minutes for the colour change to green/yellow, then add this to litre of water and wait 15-30 minutes. The mix remains stable for about a day before you need to make up a new lot.

UV radiation

Steripen products

The name sounds a bit scary, but it’s a safe way to purify wa-ter! They are small handheld units that operate electronically to produce ultraviolet light that will sterilize a litre of water in one minute. The probe is placed into the neck of a bottle and a light is observed to indicate when the process has been completed. You need a wide mouthed bottle to do this as they don’t fit in a small opening.They are effective at killing viruses, bacteria and protozoa. A prefilter is recommended for murky water.

They are light and compact, but some people have noted they don’t always work in humid environ-ments, and they do require batteries or a method of charging. CR123 batteries are not always widely available, but some can operate off rechargeable lithium batteries, or a USB port via a solar charger.Here’s an overview of the various models available: http://www.steripen.com/products/

Filtration

These have pores down to 0.3 micrometres in size, to filter out bacteria and protozoa. They do not filter out viruses, which are much smaller than this. They

can block up, so there needs to be maintenace involving cleaning and backfiltering to maintain their effectiveness. A prefilter to get rid of the obvious large stuff is advised to prolong your device’s life. It’s good to be able to collect water in a collapsible bucket (like those Sea to Summit make from sil nylon) or one of the collapsible larger Platypus water tanks and let it settle out first, and just filter the top portion. Some of these may be bulky in size in comparison to other water purification methods.

Katadyn make various brands of filters for bush-walkers: http://www.katadyn.com/en/katadyn-products/prod-ucts/katadynshopconnect/katadyn-wasserfilter/

Sawyer Filtration System

The Sawyer Squeeze Filter System has become popular recently as they are compact and can be integrated into your in pack’s in-line hydration system with some available modifications as well as being used alone.A mini version has recently come on the market which will be popular.They utilise a filter unit that is attached onto a collapsible bag filled with collected water. The bag is squeezed (hence the name) and the water passes through the filter into another

attached collection bag, or bottle or cup. It’s able to be drunk immediately. Some other types of bags

such as the Evernew brand are compatible, Platypus are not.http://www.sawyer.com/water.html

Seychelle Water Filtration Products

These are a UK company that produces many types of filters for military uses, international aid etc.Products suitable for bush-walkers include the filter bottles, inline filters, filter straws and the larger gravity filter bags.http://store.seychelle.com/

Lifestraw FiltersThese are particularly good as they are very small and compact and water can be drunk directly from the source. used often by aid agencies but lots of applica-tions in the bush.http://www.lifestraw.com.au/page/lifestraw-personal/default.asp

Overview

Some considerations to avoid getting sick from contaminated water:

- Always assume water is contaminated if there are towns, industry, farms or mines upstream

- Clear water doesn’t necessarily mean safe water - mi-croscopic hidden nasties can lurk in very clean looking water

- Avoid water downstream from popular campsites

- Defecate more than 100 metres away from water sources

- Practice good hand washing hygiene after going to the loo and before eating - clean your hands first, then disinfect

- Collect water, prefilter and stand first for best results

- Follow manufacturer’s directions with mixing and time before it’s able to be drunk