The Clean Hands Index field research is based on 350 documented public handwashing evaluations conducted at 235 operational locations over a one-year period. Each evaluation was performed in person using a standardized methodology that measures the complete public handwashing experience rather than individual fixtures. Every restroom was evaluated against the five Clean Hands Certified criteria: touch-free soap, touch-free faucet, warm water, hygienic hand drying, and a hands-free exit. In addition to the overall score, more than 20 individual data points were recorded during each visit, including fixture brands, cleanliness, attendant presence, operational issues, and engineering observations such as faucet placement, dispenser performance, towel quality, and exit conditions.

The field research was conducted across 16 U.S. states—California, Colorado, Florida, Illinois, Indiana, Kansas, Kentucky, Missouri, Nevada, New Jersey, New Mexico, New York, Pennsylvania, Texas, Washington, and Wyoming—as well as three foreign countries: France, Germany, and the United Kingdom, in addition to the United States. The dataset spans a broad range of facility types, including airports, restaurants, hotels, retail stores, office buildings, entertainment venues, government facilities, healthcare locations, and public restrooms, providing one of the most comprehensive real-world studies of public handwashing performance assembled to date.