Shulchan Arukh, Orach Chayim 163/שולחן ערוך·אורח חיים קס״ג

1Law regarding one who has no water and feeds others. Comprising two sections: If water is not available to him within four mils ahead of him or one mil behind him, he should wipe his hands with a cloth and eat bread or food that has been dipped in liquid (or eat using a spoon).

2One who feeds others does not need to wash their hands; but the one eating does need to wash their hands, even though the [other] is putting it into his mouth and he is not touching the food. And the law is the same for one eating with a magrefah (the meaning of which is an instrument with prongs, a fork in the vernacular), that they need to wash their hands. And it is forbidden to feed someone who does not wash their hands, on account of, "you shall not place a stumbling block before the blind." (Rabbenu Yonah at the end of the chapter [entitled] Elu HaDevarim)