Individual water requirements vary from person to person, and can depend on many factors such as activity level and environment. Most healthy people need to make sure they are drinking enough water, but drinking too much water is usually not an issue.
The IOM has not established a UL for water. The UL is the maximum amount of a nutrient one can likely consume without adverse effects. Each day water losses are balanced with water intake, and a healthy body has a sophisticated system that works to maintain water balance, so excess water is removed from the body through one’s urine.
See Food Composition > Macronutrients > Water (link is external) for more information. The FNIC also provides a link to DRI Tables, where you can read more about the function, and sources of water, as well as adverse effects of excessive consumption and special considerations for water intake. Go to Dietary Guidance > Dietary Reference Intakes > DRI Tables (link is external). Scroll down to see Dietary Reference Intakes: Electrolytes and Water, and then find water under the Nutrient column.