obligatory water loss

o·blig·a·to·ry wa·ter loss

(ŏ-blig'ă-tōr-ē waw'tĕr laws)
Minimal volume of urine that must be produced to dispose of dissolved wastes, which amounts to about 600 mOsm/day.
References in periodicals archive ?
Individuals who cannot concentrate urine must produce a larger volume to excrete the daily metabolic load, subjecting them to greater obligatory water loss. Water eliminated through the skin, lungs, and stool is termed insensible water loss.