It is not recommended to drink tap water in Cusco or elsewhere in Peru. The water may contain harmful bacteria or parasites that can cause illness, especially for visitors who are not accustomed to the local water supply. It is important to use bottled or filtered water for drinking, brushing teeth, and preparing food. Reputable restaurants and hotels usually provide filtered water for their guests. It is also recommended to avoid ice cubes made from tap water and to consume only fruits and vegetables that have been washed with clean water.