The commercial and institutional sector is the second-largest user of publicly supplied water in the United States, accounting for approximately 17% of total public water withdrawals. As of 2005, commercial buildings consumed an estimated 10.2 billion gallons of water per day, representing a 23% increase since 1990. In most commercial buildings, domestic and restroom use is the largest source of water consumption, while restaurants are a notable exception—where approximately 52% of total water use is dedicated to dishwashing and kitchen activities.
Source: https://css.umich.edu/publications/factsheets/built-environment/commercial-buildings-factsheet