What is the significance of the fact that, the moment Miri'am died, Yisrael ran out of water?
Rashi and Targum Yonasan (in Pasuk #1): Because their water - in the form of the well - accompanied them in the desert on the merit of Miriam. 1
See Torah Temimah, who citing the Maharsha, who discusses the apparent contradiction to this from Rashi?s comment in Vayeira - that the water in the desert was due to Avraham?s statement with reference to the three Mal?achim ?Yukach Na Me?at Mayim? ? and elaborates. Moshav Zekenim and Hadar Zekenim (both in Pasuk 1): This is a source for the custom to spill water when someone dies. We hint to the death, so people will know to perform Chesed with the Meis. We do not explicitly mention the death, since 'One who says bad matters is a fool' (Mishlei 10:18; Pesachim 3b).