Rashi on Numbers 20:2/רש"י על במדבר כ׳:ב׳

1ולא היה מים לעדה AND THERE WAS NO WATER FOR THE CONGREGATION — Since this statement follows immediately after the mention of Miriam’s death, we may learn from it that during the entire forty years they had the “well” through Miriam’s merit (Taanit 9a).