Conversion of water into steam is the primary function of a utility boiler. The steam pressure is used to turn a steam turbine thus, generating electricity. Within the boiler drum there exists a steam/water interface. Boiler steam drum water level is one of the important parameters of power plant that must be measured and controlled. For safe and efficient boiler operation, a constant level of water in the boiler drum is required to be maintained. Too low water level may cause damage boiler tube by overheating. On the other hand too high drum water level leads to improper function of separators, difficulty in temperature controlling and damage in superheater tubes. Turbine may also be damaged by moisture or water treatment chemicals carryover. The amount of water entering the boiler drum must be balanced with the amounts of steam leaving to accomplish the constant water level in the drum. Therefore it is extremely important to have the knowledge of the operating principles, installation requirements, strength and weaknesses of drum water level control system. Ignoring these considerations can result in misapplication, frequent maintenance, unsafe operation and poor instrument as well as system performance. In this paper design aspects and installation requirements of boiler drum level control are discussed for safe and economic operation.