Free Water Heatmap

[Xmudder]

I've been poking into water production / consumption after starting a game with high salinity seas.

I would like to see a heatmap of potential and actual free water production. This would make it easier to figure out what was going on, and where the best place to put zone assets on to generate free water. It would also make it easier when Vic switches over to hex by hex river, lake, and ocean production.

As it is, the numbers make no sense. Why does the zone with few rivers and 2 open sky agriculture produce more free water than the zone with a long big river and a city next to a one hex lake (605 vs 250)? Do the 14 agricultural hexes contribute to rainfall calculations? I believe it contributes to the "free" 1190 water reduction price.

Clicking on the hex gives me some interesting potential water information (rainfall, river, undergound) but not actual production.