Question on Waterer

[gwtx2]

I have 1 three gallon galvanized watering can the two piece unit. I want to drill a one inch hole in the top of the can so I can fill from outside the cage with a water hose inserted into the hole. Not sure if this type of waterer works on a vacuum or not and if the hole will affect the release of water into the base part. Anyone know?

 

[1muttsfan]

Usually they work on vacuum and drilling a hole will ruin them