1) Potential energy or potential head
It is due to the position above some suitable datum line. It is denoted by z.
2) Kinetic energy or kinetic head
It is due to the velocity of flowing liquid. Its value if givin by v2/2g, where c is the velocity of flow and g is the acceleration due to gravity.
3) Pressure energy or pressure head
It is due to the pressure of liquid. Its value is given by p/w, where p is the pressure in N/m2 and w is the weight density of the liquid in N/m3 .