Just as the name suggests, such a pump needs to be located in the bilge. This part of the boat is the one that accumulates water and, depending on the size of your boat, there can be more than one such compartment that can hold water.
Given that keeping water away from the boat is a very important task, each boat should use an electric pump for every bilge area, as well as a large manual one in case any of the electrical units fail and the situation requires water to be removed without delay.