Is it permitted for one to wash up in a sink which has been used for non kosher food?
If the sink has been used with hot non kosher food or hot water on non kosher utensils it is still permitted to wash kosher dishes there providing it is thoroughly clean and the water used is cold. If the non kosher food and utensils were only washed in cold water then the sink can be used even with hot water. If the sink is not kosher it should be kashered if used on a permanent basis for kosher dishes.
Y:D 91 Shach 3, Y:D 121:5