Drinking hot tap water can be risky due to the possibility of it containing harmful contaminants. Hot water systems can leach materials from pipes, such as lead or other metals, especially if the plumbing is old or in poor condition. Additionally, water that has been heated can harbor bacteria if the temperature is not sufficient to kill them.

It’s advisable to use cold tap water for drinking, then heat it separately if necessary. This ensures that you minimize the risk of exposure to potentially harmful substances and pathogens. Always consider why hot tap water is needed, and whether it's feasible to opt for brewing or boiling from cool water instead.