Water Tower isn't filling

I have a rather large farm, with water pumps/towers interspersed. The farther the towers are from the center of the region, the less likely they are to fill. The graph, I'm attaching, as the specifics. The lesser distance is where I am, in the center of the region, and the N & S towers are 147 - 154 meters, distant. The N & S Towers require refilling 2x a day, and two of them are servicing 84 small fields. Even so, they both go dry. The other pumps are servicing more foliage (trees, mostly) then the four pumps/towers N & S. I added the 2nd pump/tower N & S even when I had 36 fields, as 6 were dry; then, I added 48 more small fields, and only one field went dry ...but the towers were empty!

The white smudges, in the Locations file, show present pump/tower locations.

Frankly, I'm puzzled, given your exemplary explanation on watering of last week!