Q. The previous owners of the house left us a set of glasses, some glass some crystal. They haven't been used in almost two years and I'm wondering if I can use them. Do I need to kasher them and if so how? Am I allowed to wash them in my sink or dishwasher or will that make the sink or dishwasher treif.
A. The ones made of simple glass can be used as is. The crystal glasses should be koshered by submerging them in water for three consecutive 24 hour periods (Meluy Veiruy). The water should be emptied and refilled at the end of each 24 hour cycle for a total of 72 hours. You can wash them previously to remove dust in regular sink with lukewarm (less than 45º C) water.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller Shlit"a