Raw water source is one of the promising new heat sources that researchers are looking into along with various others water-based sources such as ground, lake, river and sewage water. Generally, the water that is taken from the environment and supplied to a water treatment facility is called raw water. In this study, the heating and cooling performance of a heat pump utilizing the heat energy of raw water supplied to a water treatment facility is investigated. The two heat pumps being investigated have a heating capacity of 65.2 kW and were installed at the site for the heating and cooling of the central control room. A brazed plate heat exchanger was used for obtaining heat energy from the raw water. The raw water source provides a favorable heat source compared to the ambient air source except in spring. In the seasons of spring and autumn, the heating and cooling load are extremely low, this is the main reason for the poor performance of the raw-water heat pump system for those seasons. The average unit COP during the heating season is 3.3, and the average unit COP for the cooling season is 7.2. (C) 2011 Elsevier B.V. All rights reserved.