氯化（英语：Chlorination）是水的净化中的一个过程，在这个过程中，氯气被加入水中。被处理后的水能够更有效的预防疾病传染。游泳池中的水也经常是通过氯化消毒。

Water chlorination is the process of adding chlorine (Cl
2) or hypochlorite to water. This method is used to kill certain bacteria and other microbes in tap water as chlorine is highly toxic. In particular, chlorination is used to prevent the spread of waterborne diseases such as cholera, dysentery, typhoid etc.