What is one to do if there is no water available?[1]
One is required to search for water up to a Mil’s distance from his location [i.e. 18/24 minutes] to perform Mayim Achronim. If water is not available for this distance, then one is to wipe his hands on earth or a rock, or anything else that cleans. If he later reaches water after Birchas Hamazon, he is to wash his hands, as explained next.
style="text-align: justify">If one forgot to perform Mayim Achronim before Birchas Hamazon, is it to be performed afterwards?[2]
Yes. He is to perform Mayim Achronim after Birchas Hamazon.
________________________________________________________________________________
[1] M”B 181:2; Kaf Hachaim 181:7
[2] Chesed Lealafim 181:8; Ben Ish Chaiy Shlach 11; Kaf Hachaim 181:26