1) Shot of lemon or lime juice.
Some people also find that the addition of sugar or a little honey helps to speed up the process. The citric acid in citrus fruits is what breaks down chlorine molecules – this chemical reaction happens readily if the pH is right (just acidic enough).
2) Boiling water method
This is a natural solution and involves bringing water to a boil, and then let cool (still in an open cup). Putting any type of metal into boiling water has a similar effect on driving off chlorine, making the water suitable for human consumption: