Water is probably the most important factor in colony survival. Too much water and you have mold, poor visibility, mites, and it can be bad for some ant's health. Too little water and a colony can die in only a few days.
The safest option seems to be to go easy on nest hydration, but always provide ample water feeders in the outworld.
But this is easier said than done.
Test Tube With Cotton/sponge: this is an almost fool proof feeder, but it's hard to find tubes small enough to fit in some outworlds. It's also not the most attractive option depending on the configuration of the space. To fit in my small outworlds I buy tiny little bottles and stop them up with rubber high density sponges. This option has been the most reliable. But it also can be a pain keep refilling. And the exposed surface evaporates more quickly than vertical feeders.
3D printed vertical feeders: every species of ant will react differently to these and I must verify that the ants can successfully drink from the feeder...but can't block it with sand flooding their enclosure. A feeder that has been VERY reliable for my Camponotus pennsylvanicus colonies nearly killed some of my Pogonomyrmex who insisted on packing it with sand and trash causing the water to quickly empty filling up the outworld like a horrible ocean of ants that can't swim.
I discovered that ants that seem dead after being submerged can come back to life. I also lost about 8 workers and I'm pretty bummed about it.
My point is that what has worked for months for one colony can be bad for another.
Giving my Pogonomyrmex water safely has always been difficult. I've resigned to putting in mini tubes every few days. They are very water focused ants and will cover any wet surface they can't drink with sand. Their new outworld will accommodate a test tube.
What are your favorite liquid feeders?