water budget
/ˈwɔːtə ˌbʌdʒɪt/noun
1 Heraldry. = water bouget.
2= water bouget. Now historical and rare.
3 Biology. The relationship between water intake and water loss in an organism, ecosystem, etc.
Origin
Mid 16th century; earliest use found in Gerard Legh (d. 1563), heraldic writer. From water + budget.