The aim of the present study was to analyze changes in water consumption which took place in the years 2011–2020 in the Educational-Museum Center of Poleski National Park (Poland), from which wastewater is discharged to a hybrid constructed wetland wastewater treatment plant. Water consumption was shown to be dependent on the number of visitors to the museum. As the number of visitors grew from 11,000 in 2011 to over 55,000 in 2019, the annual water consumption increased from 131 to 430 m3. Along with an increase in the percentage of individual visitors in the total number of visitors to the museum from over 40% in 2011–2017 to over 80% in 2020, water consumption per person decreased from 12.21 dm3 .d-1 to 7.18 dm3 .d-1. The average daily water consumption per one visitor in 2011–2020 was 10.4 dm3 .d-1, a value that was similar to the water consumption standard for museums (10 dm3 .d-1) set out in the Regulation of the Polish Minister of Infrastructure of 14 January 2002 on defining average water consumption standards. The average daily amount of water used in the museum building in the individual months of the year ranged from 0.12 to 1.28 m3/d. The highest average daily water consumption was recorded in the high tourist season (May–August), and the lowest in the low tourist season (January–April, September–December).