The Mississippi River is the second longest River in North America. It runs from Lake Itasca, Minnesota to the Gulf of Mexico. It is considered the US national principal river. Otamiri is a river that rises from Egbu, Imo State, reaches Ngor Okpula where it is joined by River Ogochia and then joins Imo River that empties into the Atlantic Ocean. Since these two bodies of water are located on both sides of the Atlantic Ocean, there was a need to find out the similarities and differences in their water quality, hence this study. In January 2017, water samples were collected from the Otamiri River in Egbu, Imo State from 3 sites 50 meters apart, transported to the US and chemically tested in the Alcorn State University laboratory using the LaMotte water pollution detection kits. During the month of July 2017, water samples were collected from three different sites, 50 meters apart, from the Mississippi River in Port Gibson area. They were taken to the Alcorn State University laboratory and tested. The Results of the tests on the two rivers were recorded and analyzed. The Otamiri River met the Mississippi Water Quality Criteria (MSWQC/EPA) with the exception of alkalinity, Carbon dioxide, and phosphate. Coliform bacteria were negative. The Mississippi River met the MSWQC with the exception of alkalinity, Carbon dioxide, dissolved oxygen (Low), hardness, and phosphate. Coliform bacteria tests were negative also. Of all the differences and similarities., the most outstanding was the Mississippi River’s very high water hardness concentration and Otamiri River’s none existence of hardness.