Water water everywhere but not a drop to drink.


The cycling tourist may find themselves exposed to the organisms that can cause diarrhoea.  E.Coli, Shigella, Entamoeba histolytica, Giardia, Cryptosporidiosis.  Don’t assume that water at that rest stop  is safe to drink, even if it comes from a tap.  The water may look crystal clear but could contain various bacteria that can cause illness, and the last thing you need when cycling is running.

Unless it is posted on the tap/tank or a local has told you that the water is safe to drink.

There are several methods to purify water, some are more effective than others. The decision on which method to use should take into consideration the likely level of contamination of water along your journey and whatever is deemed the most practical and acceptable to you.

The main methods of water purification are:

  • Boiling
  • Filtration
  • Chemical
  • Sterilisation


This is the most reliable method, although stoves, kettles and camp fires may billybe inconvenient, but think of the consequences of not doing it. Boiling is an excellent way to make contaminated water safe to drink but takes time and you need the necessary gear (some way to heat the water) must be done in small batches, requires pouring hot water into containers and then waiting for the water to cool, and uses up your limited fuel supply.

To boil water properly it should be kept at a vigorous, rolling boil for at least one minute and at altitudes above 2000m the water should be boiled for three minutes and at higher altitude for up to five minutes (at 5800m water boils at 180c). Water purified in this way should be cooled and covered to avoid contamination after boiling.


A wide variety of filters are available and prices vary accordingly.

Filter pore size determines how effective a filter will be, although micro-organisms will also adhere to the filter material.  Filters are usually effective at removing bacteria and parasites but may not adequately remove viruses.  If this type of filter is used, filtered water must also be chemically treated, boiled or use an UV light.  Good filters are effective against cryptosporidium and giardia.

Filtering water can be a good way to decontaminate water but its effectiveness varies depending on the quality of the filter. It is important that the filter you use filters not only viruses but bacteria as well. There are several types of filters on the market and can be divided into three main types:

Gravity filters slower, bigger and generally less effective, gravity filters work by allowing water to drain down via an inner core, usually in the form of an iodine or charcoal impregnated element. Most are slow and should only be considered as a backup or if you have plenty of time on your hands with nothing better to do.

Manual filters these are an improvement on gravity filters and work by msr-miniworksforcing water through a micro-porous ceramic filter, sometimes in conjunction with a chemical element.  These types of filters are ideal for the travelling cyclists.  However, they are more expensive than gravity filters but they provide safer drinking water at a much quicker rate of about 0.5 – 1 litre per minute.  The ceramic cores needs regular cleaning, especially when filtering sedimented water (pre-filtering with a Millbank filter or using a coffee drip filter wrapped around the inlet end of your hose, this will help reduce cleaning, and it can help the filter last for 1000’s of litres.  The ceramic filters are usually 2 to 3 microns is size.

Millbanks Filters – This type is a portable water filtration device made of tightly woven millbankcanvas made for use out of doors.  They are light, compact and easy but very slow to use.  The bag is filled with water, which filters through the canvas by gravity. It is useful for removing sediment and organic matter but the water will require further sterilisation before being drunk. Would make a good pre-filter if you had the time in your hands.


There are two types of chemical treatment: those using iodine and those using chlorine. There are a variety of products on the market, so follow the directions on the bottle or the packet.  Point to note, that tablets have an expiration date and become ineffective after that point, usually six months once the bottle is opened.  If in doubt, buy a new bottle and be done with it.  Remember to check the expiration date when buying your tablets.

Remember that chemical purification methods may only be partially effective, depending on micropurthe water temperature.  Water purification tablets, such as Katadyn Micropur tablets, Aquatabs, Oasis water tabs or Coghlan’s emergency Germicidal tablets (sounds yummy) are some of the brands available in Australia.  Tablets are easy, inexpensive, and quick, but can affect the taste of the water.   Another issue is that chemicals are ineffective against some protozoa, such as cryptosporidium, and require much longer to work if the water is full of sediment or is very cold.

  • The effectiveness of all chemical treatment of water is related to the temperature oasisof the water, pH level, and clarity of the water.  Cloudy water often requires higher concentrations of chemical to disinfect.
  • If the water is cloudy or contains large particles, strain it, using a filter or thick cloth, before treatment.  Large chucks, if swallowed, may only be purified externally”.
  • Add the chemical to the water and swish it around to aid in dissolving. Use some of the aquatabstreated water onto the lid and the threads of the water bottle so that all water areas are treated.
  • The water should sit for at least 30 minutes after adding the chemical (liquid) to allow purification to occur.  If using tablets, let the water sit for 30 minutes after the tablet has dissolved.

Be aware that some people are allergic to iodine and cannot use it as a form of water purification.     

Ultraviolet (UV) Radiation.

The SteriPEN uses ultraviolet light (UV) to purify water.  The SteriPEN, steripensabout the only UV touring size tool I could find heaps on.  The UV light destroys viruses, bacteria and protozoa (such as giardia and cryptosporidium), and according to company literature, exceeds US EPA standards for microbiological water purifiers.  The SteriPEN has a problem with treating murky or muddy water and recommend pre-filtering which sounds like a good idea even before knowing about the murky problem.

You push the button once, immerse the UV lamp, stir continuously, and you’ve got one litre of safe water in 90 seconds.  For a half litre you push the button twice and wait only 48 seconds.

Other disadvantages of UV sterilisation are you need batteries, the possibility of electronic failure, although there is now a USB rechargeable pen so those touring with solar this may be the way to go.

So on closing, the SteriPENs are convenient, quick and easy to use. However, they’re only good for small batches pretty much the same as boiling water method.

Always have at least one backup method for your water purification in case one fails. This can be any combination of methods.  There’s always boiling the water, just make sure you have enough fuel or can find enough.