A person went to work on chol hamoed pesach (a non Jewish workplace), and they filled their kosher-for-pesach mug with hot water from the office urn that was not in any way kashered for pesach. Is the mug still ok for pesach use (for next year)?
[If it makes a difference, the mug is a kli cheres (glazed ceramic)]
For next year, you should be careful not to use a urn that was not koshered for Pesach, because it might have been used for chometz, (making oatmeal or other hot cereals). In retrospect however, you can use the mug for Pesach next year. This is since it is only questionable if the urn was indeed chometz or not, therefore we can rely on the fact that it waited so long since it was used.