Coal based thermal power plants (CTPPs) need water in huge quantities, and hence have a significant impact on water resources in the surroundings. However, it is generally assumed that few such concerns exist with respect to coastal coal based power plants as they use sea water, which is available in virtually unlimited amounts. This is fallacious thinking, because it is based on an understanding that sees the use of water by CTPPs only in arithmetic or algebraic terms. In reality, the impact of CTPPs on water is multi-faceted and based on a multi-dimensional, complex relationship. This report brings out such impacts of coastal thermal power plants based on field visit to several such projects.