Eau or EAU may refer to:

• The French word for water
• Eau (trigraph), a trigraph of the Latin script
• EAU, the IATA code for the Chippewa Valley Regional Airport in Wisconsin, United States
• East Africa University, a private university in Puntland, Somalia
• El Asher University, an undergraduate university in the Sharqia Governorate, Egypt
• Emergency assessment unit (EAU), a short-stay department in a hospital
• Estimated annual usage (EAU)
• European Association of Urology, a non-profit organisation of urology professionals
• Initiative: Eau, an American nonprofit, non-governmental organization
• River Eau, a tributary of the River Trent in Lincolnshire, England