An aquifer isn't an endless water sources. If you extract a lot of water and then evaporate it, it will lose water over time and go dry. So the whole project is doomed from the start of more than a few people try to live there.

Then you run into the big problem of how to measure moral cost. There will be situations where you can minimise monetary cost by increasing the moral cost. To minimise for both you need to put a price tag on morality in dollars. How much does a dead civilian cost?