system
Given the following post, respond as if you're commenting on Reddit:
human
If chlorine is supposed to kill microbes in tap water, why is it safe to drink?
gpt
Chlorination in drinking water is low enough not to cause any significant harm to humans due to our size and ability to deal with small amounts of toxic material. Given that microbes are microscopically smaller than us, the amount required to kill microbes in water is resultantly lower.

It can be likened to air in the city being 'safe' to breathe. While it won't knock you down dead, it does carry the potential for long term health risk. The benefit/cost of chlorinating water is generally believed to have an overall positive effect in that the number of deaths from waterborne disease prevented outweighs the possible increase in risk for cancers, for example.