Water Treatment

Drinking water designed for human consumption in many countries is often less safe than what can be expected here at home. In some cases drinking water can be the cause of typhoid, dysentry and cholera as well as the more normal stomach upsets. Often when traveling drinking water from places such as rivers, lakes and bogs is a necessity and quality cannot be guaranteed at all. In all of these cases purification of the water is imperative.

Water purification either takes the form of sterilisation by boiling or UV light, chemical treatment, filtration or a combination of these.

The first step in treating water is to check whether the water is clear or cloudy. If cloudy or muddy it is useful to strain the water through some fine cloth. This will mean that you don't have to use so many chemicals to treat the water and it will make filtering easier and extend the life of your filter.

Boiling water vigorously for 1 minute before allowing it to cool naturally to drinkable temperature will kill bacteria, parasites and viruses. Above 2000m water should be boiled for 3 minutes. If boiling water is not an option then you will need to look at treatment and filtration.

Treatment

Treatment is the addition of chemicals to water to kill any pathogenic organisms that are present. The two main options for this are chlorine and iodine. It is important to note that the measurements described below are for clear water above 5°C. For cloudy water you will need to double the amount of treatment used and for cold water double the treatment time.

Chlorine is a widely used safe treatment that we stock in tablet form from Lifesystems. Tablets have the advantage that they give easy to measure dosage, ie 1 tablet for each litre of water, however. One pack of tablets will treat 75 litres. Chlorine is less reliable in cloudy water when iodine should be considered, it also isn't sufficient to protect against Giardia or Cryptosporidium, so if Giardia is likely to be present in drinking water then you need to consider iodine.

Iodine is effective protection against Giardia as well as those pathogens covered by chlorine and comes in tablet and liquid forms from Lifesystems. Iodine is not recommended for prolonged use (anything greater than 3 months) as it comes with its own issues. Also, if Cryptosporidium is likely to be present in drinking water then you need to consider filtration or sterilisation.

Neutralising Tablets can be added to treated water to reduce bad tastes. It works in the same manner as treating the water, ie the treatment chemical attaches itself to the impurities, and any treatment that is left over leaves a bad taste which the neutraliser can attach itself to. All the Lifesystems Chlorine and Iodine products come in a small plastic case with a handy cloth filter inside.

Sterilisation

The newest concept in processing water for drinking is sterilisation with UV light. The SteriPen is small, AA battery powered and extremely effective against viruses, protazoa (including Giardia and Cryptosporidium) and bacteria. While a bit more fragile than conventional ceramic filters, it is a lot lighter and has no filter that will need replacing over time. We find it to be an excellent option for most uses!

Filtration

Filtration is the use of a device to filter water through it to remove protozoa, bacteria, cysts and in some cases viruses. All of the filters that we stock will need the actual filter part (usually ceramic) of the device replacing after certain periods.

The quality of filtration depends on the pore size of the actual filter. Protozoa are 3-20 microns and bacteria are 0.5-5 microns in size and will be removed by any filter that we stock as the maximum pore size of any of our filters is 0.3 microns, this means that Giardia and Cryptosporidium will also be removed. Viruses on the other hand are 0.01-0.25 microns and cannot be removed by travel filters and therefore it is always important to treat water with chlorine or iodine before filtering, or use the SteriPen.

The ease of filtration depends on the type of filter used. Trek Mates produce our simplest filter, the Travel Well Pocket Water Purifier, which works like a straw. It is inexpensive, light and compact and feels like drinking a thick milk shake through a straw. The McNett Aquamira Bottle is a useful option that has a 0.3 micron pore size that is basically a water bottle with a filter in the lid, again drinking from it is harder work than a normal bottle but this is a very useful way of filtering at a minimal price.

For mechanical filters that you actually pump water through, take a look at the MSR Mini Works or the Katadyn Mini Ceramic and Combi Filters. The Mini Ceramic Filter has a flow rate of 0.5 litre-min and due to its size and light weight is only any use on clear water- it tends to block and break if used with cloudy water. This is ideal for single person short trips when filtering from taps or clear river water. For larger volumes and dirtier water you need to look at the SteriPen or the Combi Filter and Mini Works which have a rate of 1 litre-min and have more robust pumps, so they are ideal for small group 1 -4 people use on longer trips. They have a cartridge life of around 2000 litres if the water is fairly clear, but the life becomes shorter the cloudier the water is, so do try to strain the water through a cloth before you filter to get as much debris out as possible and to prolong the filters life. These two devices have carbon filters along side the ceramic portion that will filter out the taste of iodine and chlorine.

Summary

In conclusion the key factors for drinking safe water are:

• If possible boil water for 1 minute, no other purifying required,
• If boiling is not possible treat with chlorine based products or use the SteriPen,
• If boiling is not possible and Giardia is likely to be present and the trip is short treat with iodine products or Steripen,
• If boiling is not possible and Cryptosporidium is likely to be present (or if the trip is long and Giardia is likely to be present) treat with chlorine products and then filter, or use the SteriPen.

A note of caution regarding the use of filters is that any imperfections in the filter which may be present from the point of production may be enough for some organisms to get through so always combine filtration with treatment if possible and wherever possible attempt boiling.

Travel tips

• Avoid ice in drinks.
• Check that the seals on bottled drinks are unbroken.
• Don't allow the drink vendor to wash any dust off the sealed bottle.
• Wash your hands regularly and always before eating.
• Use treated water for washing teeth.
• Only drink pasturised milk and dairy products.
• Poured drinks such as tea, coffee, beer and wine should be fine but hand mixed fruit drinks should be avoided if possible.
• Raw fruits, veg and salads need to be washed in treated water before use.
• Fruits that are sealed such as bananas and oranges are good food options.
• Order food well cooked.
• Avoid lightly cooked food such as seafood, butter, mayonnaise, ice cream, etc.
• Avoid street vendor food or any food that has been allowed to stand for a while after cooking.
• Avoid submerging your head when swimming.