Drinking Water

This is one of the items unfortunately will cost a lot of money to fix.
Currently we are doing nothing.
The world is running out of drinking water.
Soon wars will be fought over water and food, not oil.
We need to build huge desalination plants up and down both coast of the United States that simply convert salt water (an abundance on earth) to fresh water. The salt residue then becomes table salt.
In addition to these plants we need pipelines that carry fresh water throughout the United States especially to areas that produce food such as crops and livestock.
Plant designs should be a tinker toy replicator design, as in all the plants are exactly the same. This reduces various design, engineering, and construction cost and maintenance and replacements parts are all interchangeable.
Since we needed these 10-years-ago and have done nothing, we better get our head out of our butts and start building about 100 of these now, plus at least 5 major pipelines across the country with multiple spurs to bring the necessary fresh water to critical areas.
Man cannot not survive without drinking water.
We can not grow crops and feed livestock without it.