I use a separate water bottle with a longer sipper for the babies.
They technically could keep nursing off mom longer until they're large enough to reach the normal drinking valves. But I find that when they start drinking water sooner, they're weaned at a much faster rate. So I like giving them that option of a long water sipper. Before I started using the longer sipper bottles, I just turned over a ceramic crock in the tub and they used it like a step to reach the water. (<<-- wasn't as efficient though)
And food, I just put them in a bowl or transfer the rats to a tub where there's a lowered feeding hopper.