Water is essential for life and for a mass of productive activities. Today, the most easily accessible parts of renewable freshwater resources have already been exploited. Generally, a country or a region will experience water scarcity when water supplies fall below 1000 cubic meters per person per year. Thus, rapid population growth is leading to alleviate food problems and increasing water scarcity.

Optimizing food production per unit water is becoming essential to sustain agriculture, conserving water, meeting the increasing demand on food and fiber. The objectives of this study were: first, to estimate the water production efficiency, and second to model water need for agriculture as a function of per capita daily consumption.

To estimate the minimum water requirements needed to produce the different food ingredients for a balanced diet per capita per day a linear programming model was used. Three scenarios were used, where each scenario was subjected to certain constraints. The first scenario was subjected to serving constraint, the second scenario was subjected to calorie constraint and the last scenario was subjected to, serving, calorie, and budget constraint.

The economic constraint had been formulated into four different alternatives of budgets, starting from 3000 to 11000 LL. Also item prices were changed to reflect the prices for three different periods according to cost price index. There were slight differences between the minimum water requirements among the three scenarios, but a substantial difference was among different alternatives in scenario three. The minimum water requirement decreased with allowable number of servings per person on a daily basis, this decrease followed a hyperbolic shape for each budget allocation. On the other hand, there was a linear relationship between the minimum water required per capita per day, and the budget allocated per person on daily basis.

The results showed that the net minimum water required for a healthy diet was 790 cubic meter per capita per year and a net maximum of 1332 cubic meters per capita per year. The results obtained will help the decision makers to allocate the needed water for agriculture as a function of food consumption and population growth.