"Adequate Intakes (AI) have been defined derived from a combination of observed intakes in population groups with desirable osmolarity values of urine and desirable water volumes per energy unit consumed. The reference values for total water intake include water from drinking water, beverages of all kind, and from food moisture and only apply to conditions of moderate environmental temperature and moderate physical activity levels (PAL 1.6). [...] Available data for adults permit the definition of AIs as 2.0 L/day (P 95 3.1 L) for females and 2.5 L/day (P95 4.0 L) for males."
"The minimum water requirement for fluid replacement for a 70kg human in a temperate zone equates to 3L per day, or 42.9mL/kg [according to the Tropical Agriculture Association]. Minimum requirements for an individual the same size but in a tropical zone equates to 4.1 to 6L/day"
"Age and gender specific Adequate Intakes (AI) for water were established in 2004 by the [United States] Food and Nutrition Board (5). The Dietary Reference Intakes (DRI) for water are [for ages 19 and older] Men 3.7 L/day Women 2.7 L/day"
The recommended amount depends on who does the recommendation but 1.9L doesn't seem high.
https://www.efsa.europa.eu/fr/efsajournal/pub/1459
"Adequate Intakes (AI) have been defined derived from a combination of observed intakes in population groups with desirable osmolarity values of urine and desirable water volumes per energy unit consumed. The reference values for total water intake include water from drinking water, beverages of all kind, and from food moisture and only apply to conditions of moderate environmental temperature and moderate physical activity levels (PAL 1.6). [...] Available data for adults permit the definition of AIs as 2.0 L/day (P 95 3.1 L) for females and 2.5 L/day (P95 4.0 L) for males."
https://apps.who.int/iris/handle/10665/43403
"The minimum water requirement for fluid replacement for a 70kg human in a temperate zone equates to 3L per day, or 42.9mL/kg [according to the Tropical Agriculture Association]. Minimum requirements for an individual the same size but in a tropical zone equates to 4.1 to 6L/day"
"Age and gender specific Adequate Intakes (AI) for water were established in 2004 by the [United States] Food and Nutrition Board (5). The Dietary Reference Intakes (DRI) for water are [for ages 19 and older] Men 3.7 L/day Women 2.7 L/day"