How to Discard Fat

At some point, you have to throw out the fat. You can’t use the same batch over and over forever, because the fat was cooked with foods that are capable of producing bacteria if left to sit around long enough, and it can take on the flavor of whatever you are cooking. After the fat has been rendered, we recommend using it only once, and then discarding the used portion. So what is the proper way to toss it?