The tap water in Madrid hotels is generally safe to drink. According to the World Health Organization (WHO), Spain has a well-treated drinking water supply, and the tap water in Madrid meets all international safety standards.
In fact, many locals drink tap water without hesitation, as it’s considered reliable and clean. However, if you’re extra cautious or prefer bottled water for personal preference, there are plenty of options available at supermarkets, convenience stores, or even your hotel room.