Droppings the size of apple pips if not slightly bigger, Hairs, tail swipes, smell, chewing / gnawing to personal belongings, noises in wall cavities and ceilings especially at night.

 

Rats can carry and pass on several serious diseases to humans such as, salmonella, leptospirosis, typhus, Rat bite fever. 

 

Rats need shelter, food and water to survive. They wont live far from a food and water source.