Most enteral formulas contain 80-85% free water, and fluid needs can be met with a small amount of additional water. However, calorically dense formulas contain as little as 60% free water, so the failure to supplement water with the denser formulas can result in dehydration.

Fluid requirement: 2000ml
Formula intake: 2200ml
Formula: 80% free water

2500ml formula x 0.80 = 1760 ml free water

Additional water needs:

2000ml - 1760ml = 240ml water

practice calculations