How to teach rabbits to drink from a water bottle?

Why won't my rabbits drink from their water bottle? They will only drink from dishes. I made their bottles drip into their dishes for a day, then took away the dishes, but they just didn't drink. When I put the dishes back in they rushed over very thirsty, so I haven't tried again because I don't want to dehydrate them. Any tricks to switching them over? Dishes are a pain!