1)
WHEN THERE IS ONLY ENOUGH WATER FOR ONE PERSON
לכדתניא שנים שהיו מהלכין בדרך וביד אחד מהן קיתון של מים אם שותין שניהם מתים ואם שותה אחד מהן מגיע לישוב דרש בן פטורא מוטב שישתו שניהם וימותו ואל יראה אחד מהם במיתתו של חבירו עד שבא ר׳ עקיבא ולימד וחי אחיך עמך חייך קודמים לחיי חבירך
Translation: He requires it for what was taught in the following Baraisa: Two who were traveling on the road, and in one's hand is a pitcher of water. If both of them drink they will both die. If one of them drinks, he will reach a settlement. Ben Petorah taught: Better they both drink and die, and that one will not see the death of the other. Until Rabbi Akiva came and taught: 'That your brother may live with you' means that your life comes before the life of another. ('With you' implies that your life comes first.)
(a)
What would be the law if the water was owned by both of them?
1.
Maharsha: It could be that even R' Akiva would agree with Ben Petorah that they should both die rather than see the death of each other. In such a case, we would say to each one of them, "Who says that your blood is redder?" (which is the logic used to say that one Jew may not put to death another in order that the first Jew will live).