[header] How to keep a pet rat clean [title] Fill the sink with an inch of warm water. [step] The water temperature should be a comfortable warm temperature similar to what you would want in a bath-not too hot and not too cold. Since rats are fairly small, you only need to fill the sink with about an inch of water for the bath. 
[substeps] Make sure the water stays warm throughout the bath. If the water starts to cool off too quickly, add some more warm water to the bath.