Rats can enter a building through a hole as small as 1/2 inch in diameter. They are strong swimmers, so, rats will live in sewers and can enter buildings through broken drains or toilets. A rat will climb to get to the food, water, or shelter. Rats follow regular routines and paths each day. If new objects are set in its path, it will do whatever it can to avoid it. Rats usually stay within 300 feet of their nest or burrow.