The us and ussr were all ones during world war lol in order to defeat

They created the Allied Forces to defeat the Axis Powers. (Germany, Italy, and Japan)

this means that germany had to pay the allied countries. reparations are/is essentially payment for something that they have done wrong, so after ww1, germany was forced to pay reparations so they could replenish the allied countries resources' that they had lost during the war.

worldwide, 780 million people do not have access to an improved water source. an estimated 2.5 billion people lack access to improved sanitation (more than 35% of the world's population)