Water can contain germs (such as bacteria and viruses) and chemicals which can be harmful and make you unwell. Both tap and bottled water may not be safe if it has not been produced under proper conditions, even if it is clear and colourless.
- Water should only be used for drinking and preparing food if is known to be safe.
- This also applies to water used for making ice cubes and cleaning teeth.
- Illnesses caused by food and water are more common in countries that have lower levels of hygiene.
You should only use water for drinking, making ice cubes or cleaning teeth if it has been:
- bottled or canned by a known manufacturer and the seal is intact
- boiled and cooled and stored in a clean container
- chemically disinfected or passed through a reliable water filter and stored in a clean container
Even where bottled water is readily available, it is a good idea to have a backup system for making water safe in case you run out of bottled water.
- Treating water yourself is also generally agreed to be more 'environmentally friendly' than using bottled water since the same plastic bottle can be reused and refilled.
Water treatment removes the germs from water to make it safe for you to drink. There are several different methods of purifying water. Some are more effective than others.
The method you use will depend on:
- how contaminated the water is
- which method is going to be most practical and easy for you to use
Bringing water to a rolling boil for one minute is the simplest way to kill most types of germs, even if the water is cloudy and at high altitudes.
- If water is cloudy, allow it to settle and filter through a clean cloth or coffee filter before boiling.
- You will need to boil water for around three minutes if you are at an altitude over 2000m (6500 feet).
- After water has been boiled, it should be removed from the heat and allowed to cool naturally (without adding ice):
- it should be stored in a clean container to prevent it becoming re-contaminated with germs.
- Boiling won't improve the taste, smell or appearance of the water.
If you are self-catering or visiting friends and relatives boiling may be the easiest method of water treatment as equipment and electricity or a heat source is readily available.
For other types of travel, it might not be convenient for you to carry a stove, kettle or heating coil whilst travelling.
- If you cannot boil water, then you should use other methods to safely disinfect water. This can include the use of water filters, chemical disinfectants, or UV light radiation.
Water filtration removes germs by physically blocking them while letting the water pass through the filter. Unfortunately, filtration will not remove all the germs that can make you unwell.
There are a wide variety of filters to buy and these vary in cost and how effective they are at removing different types of germs.
- Filters for treating water when travelling should not be confused with versions designed only to remove odour and chlorine from water at home.
- You should always read the information provided by the manufacturers and follow their instructions carefully.
Because filters collect germs from water, you should wear gloves whenever possible and wash your hands carefully after using or changing a filter. If you have a weakened immune system, you should avoid changing filters if possible.
Chemical disinfectants for treating water are available to buy in liquid and tablet form.
You should always follow the manufacturer's instructions. How well the chemical disinfectant works will depend on:
- the temperature of the water
- how cloudy the water is
- how long the chemical needs to be in the water to kill the germs
The most common chemical disinfectant preparations use chlorine such as Chlorine Dioxide (chemical symbol ClO2).
- It is simple to use and is available in liquid or tablet form.
- It is non-toxic and effective at killing most bacteria and viruses.
- It will not kill all germs.
- You should combine chemical treatments with another method such as boiling or filtration.
Iodine for the purpose of water treatment is no longer recommended and is not available to buy within the UK.
UV light kills germs in water and can be used as an alternative to chemical disinfection. A portable, battery operated device can be purchased that delivers a measured, timed dose of UV light.
- This method can be effective in treating small quantities of clear water.
- The manufacturer's instructions must be followed to confirm the length of time needed for treatment.
- This method will not work in cloudy water.
Salt electrolysis works by using a hand-held battery powered product which passes an electrical current through a solution of salt and water (brine). This creates a solution that you then add to the untreated water to kill the germs.
- Most organisms are killed when using this method, but it is unlikely to work against cyclospora.
Equipment for treating water and water filters can usually be purchased at outdoor sports, camping and adventure shops, or online. Please note this list is not exhaustive:
The manufacturers information should always be checked before purchase to make sure the product will get rid all of the organisms that you may be at risk from.