How to calculate the production water flow of your seawater purification system?

In a word, how much output you need ?

The World Healthy Organization recommended that one person need at least one liter fresh water per day for survival. Actually, water usage varies enormously, it is difficult to give a precise answer on average water use, approximately 125 L ~ 150 L fresh water for domestic water per person per day, showering, washing clothes etc. included. Calculating with this regular, for example, 100 person need approx 12500 L ~15000 L production fresh water per day