Lesson 38 Water and the traveller
Contamination of water supplies is usually due to poor sanitation close to water sources, sewage dis
posal into the sources themselves, leakage of sewage into distribution systems or contamination with
industrial or farm waste. Even if a piped water supply is safe at its source, it is not always safe
by the time it reaches the tap. Intermittent tap-water supplies should be regarded as particularly
suspect.
Travellers on short trips to areas with water supplies of uncertain quality should avoid drinking ta
p-water, or untreated water from any other source. It is best to hot drinks, bottled or canned drink
s of well-known brand names -- international standards of water treatment are usually followed at bo
ttling plants. Carbonated drinks are acidic, and slightly safer. Make sure that all bottles are open
ed in your presence, and that their rims are clean and dry.
Boiling is always a good way of treating water. Some hotels supply boiled water on request and this
can be used for drinking, or for brushing teeth. Portable boiling elements that can boil small quant
ities of water are useful when the right voltage of electricity is available. Refuse politely any co
ld drink from an unknown source.
Ice is only as safe as the water from which it is made, and should not be put in drinks unless it is
known to be safe. Drink can be cooled by placing them on ice tather than adding ice to them.
Alcohol may be a medical disinfectant, but should not be relied upon to sterilize water. Ethanol is
more effective at a concentration of 50-70 per cent; below 20 per cent, its bactericidal action is n
egligible. Spirits labelled 95 proof contain only about 47 per cent alcohol. Beware of methylated al
cohol, which is very poisonous, and should never be added to drinking water.
If no other safe supply can be obtained, tap water that is too hot to touch can be left to cool and
is generally safe to drink. Those planning a trip to remote areas, or intending to live in countries
where drinking water is not readily available, should know about the various possible methods for m
aking water safe.
RICHARD DAWOOD Travellers' Health