If your eggs are pipped already, I wouldn't open the lid to add water. I found out the hard way that opening the lid even for 5 seconds can be fatal to chicks that have already pipped. A rush of room temperature air gets in there very quickly and dries out the membrane, making it extremely difficult for the chicks to get out. When I did that, the two that were pipped ended up having "dryer sheet" membranes...when they were hatching the two parts of the egg shell were separated with the chick in the middle, but the outer membrane clung to both sides of the shell like crazy - and as the chick hatched it was shredded by the claws on his toes. This left 'strings' everywhere of membrane stuck to both sides of the shell. It looked exactly like a dryer sheet (fabric softener sheet texture). Eventually, the chicks DID hatch that had this problem (I didn't help them). They just got lucky and their feet were flinging everywhere and their claws eventually got lucky and clipped off enough of the strings that they could barely eek out of there.
Sorry so long - but I wanted to include the story of what happened when I tried to add water with pipped eggs.
Now what I do is put a straw inside one of the air holes and add water via funnel so I don't open the lid.
