饮用水自身不会真正“变坏”——它既不含蛋白质也没有糖,不会腐烂、发霉或者发酵。但如果水是在打开的容器中保存,水的化学成分就会发生变化。它吸收二氧化碳,一部分液体就会转化成碳酸。这虽然只是很微小的一部分(大约0.13%),但足以降低水的p H值并让口感变得有酸味。通常自来水和矿泉水中含有可以杀菌的氯,一般来说在空气中放一天仍可以 Drinking water does not really “spoil” itself - it contains neither protein nor sugar, does not rot, mold or ferment. However, if water is stored in an open container, the chemical composition of the water changes. It absorbs carbon dioxide and some of the liquid is converted to carbonic acid. Although this is only a tiny fraction (about 0.13%), it is enough to reduce the p H of water and make it sour. Normally, tap water and mineral water contain chlorine which can be sterilized. In general, it can still be put in the air for a day