What is the difference between positive and negative head?

A gravity-fed system is either positive or negative head. In a positive head system a water flow rate of at least 2L/min exists from gravity alone. In negative head systems the water flow rate is less than 2L/min.

When choosing which pump you need it is important to know if the system is positive or negative head as incorrect selection can mean the pump won’t work.

A positive head pump will only work in a positive head system and a negative head (universal) pump will work in both a positive and negative head system, so if you are not sure choose a negative head pump.

Click here to learn how to determine if your system is suitable for a positive head pump.