Negative head shower pumps rely on gravity to move water from a lower point in the plumbing system to a higher point. This makes them a perfect fit for low-pressure and gravity fed systems since the pump will be placed either level with or higher than the cold water tank. Their strength is such that they can generate more pressure compared to mains water supply.Positive head shower pumps use an electric motor to generate power and increase the pressure of the water inside the pipes. They are typically used in high-pressure systems where additional power is needed, such as with multi-level buildings or homes with multiple showers.