Before revision: Upper: traditional method of carrying water; lower: more water can be transported easily using the roller The Hippo water roller, or Hippo roller, is a device used to carry clean water more easily and efficiently than traditional methods, particularly in the developing world and rural areas.
After revision: Upper: traditional method of carrying air; lower: more water can be transported easily using the roller The Hippo water roller, or Hippo roller, is a device used to carry clean water more easily and efficiently than traditional methods, particularly in the developing world and rural areas.