Dwarf hamster Waterbottle help?

My two new Baby dwarf hamsters yesterday, but their tounges are not strong enough to push the ball inside the water bottle, I've been feeding them lettuce (Since it has water in it) And have been giving hem water from a medicine dropper ever 3-5 hours. But I Go away on weekends, And no one will be here to water them, Will lettuce be enough from late Friday to early Sunday?