水源污染通常源于以下几种情况：水源附近卫生条件恶劣、污水直接排入水源本身、污水渗入输配水系统，或受工业废水及农业废水的污染。
Contamination of water supplies is usually due to poor sanitation close to water sources, sewage disposal into the sources themselves, leakage of sewage into distribution systems or contamination with industrial or farm waste.
即便管道供水在水源处是安全的，也不一定能在流到水龙头时仍然安全。
Even if a piped water supply is safe at its source, it is not always safe by the time it reaches the tap.
间歇性自来水供应应被视为尤其可疑。
Intermittent tap-water supplies should be regarded as particularly suspect.
前往饮用水质量不确定地区短期出行的旅行者，应避免饮用自来水，或来自其他任何水源的未经处理的水。
Travellers on short trips to areas with water supplies of uncertain quality should avoid drinking tap-water, or untreated water from any other source.
最好坚持饮用热饮，或知名品牌的瓶装、罐装饮品——灌装厂通常遵循国际水处理标准。
It is best to keep to hot drinks, bottled or canned drinks of well-known brand names-international standard of water treatment are usually followed at bottling plants.
碳酸饮料呈酸性，相对而言略微更安全一些。
Carbonated drinks are acidic, and slightly safer.
务必确保所有瓶子都在你面前开封，且瓶口清洁干燥。
Make sure that all bottles are opened in your presence, and that their rims are clean and dry.
煮沸始终是处理饮用水的好方法。
Boiling is always a good way of treating water.
一些酒店会应要求提供煮沸过的水，这种水可用于饮用或刷牙。
Some hotels supply boiled water on request and this can be used for drinking, or for brushing teeth.
便携式煮水加热棒在能获得合适电压的情况下很有用，可以将少量水煮沸。
Portable boiling elements that can boil small quantities of water are useful when the right voltage of electricity is available.
礼貌地拒绝任何来源不明的冷饮。
Refuse politely any cold drink from an unknown source.
冰块的安全性仅与制作它所用的水相同，除非已确认安全，否则不应放入饮品中。
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.
饮品可以通过放置在冰上冷却，而不是将冰块加入其中。
Drinks can be cooled by placing them on ice rather than adding ice to them.
酒精可以是一种医用消毒剂，但不应依赖它来净化饮用水。
Alcohol may be a medical disinfectant, but should not be relied upon to sterilize water.
乙醇在浓度为50%至70%时效果最佳；低于20%时，其杀菌作用可以忽略不计。
Ethanol is more effective at a concentration of 50-70 percent; below 20 per cent, its bactericidal action is negligible.
标注为95酒度（proof）的烈酒，实际上仅含约47%的酒精。
Spirits labelled 95 proof contain only about 47 per cent alcohol.
要警惕甲基化酒精（变性酒精），它毒性极强，绝对不应加入饮用水中。
Beware of methylated alcohol, which is very poisonous and should never be added to drinking water.
如果无法获得其他安全水源，热到无法用手触摸的自来水可以放置冷却，通常是安全的饮用水。
If no other safe water supply can be obtained, tap water that is too hot to touch can be left to cool and is generally safe to drink.
计划前往偏远地区旅行、或打算在饮用水不易获得的国家居住的人，应当了解各种可能的水质净化方法。
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 making water safe.