For calculating the discharge head of the pumps, we need the following details of the suction and discharge side of the pumps
1. total length of the line
2. Maximum vertical rise of the liquid on the discharge side (static head on the discharge side) 
3. Vertical distance between the pump suction and the outlet of the tank being drained (static head on the suction side)
4. no. of bends
5. no. of valves
6. Details of any other fittings on the line 