microwaves

Question

Kavod HaTorah! I bring food to work everyday and I would like to warm it up in the microwave. There is a microwave that is used by about 3 people about once a day. Can I just warm up my food in the microwave bymaking sure that it is covered and giving the microwave a "good cleaning"? Or must I boil water in there first? Hatzlacha! - Shmuel