Many processing plants need good quality water to feed the steam boilers and heat recovery coils of process heaters. Some plants also may require good quality water for their process. Most plants obtain fresh water either from the city utility water supply or by pumping from ground wells. However, fresh water from natural resources usually contains dissolved minerals. Some, such as calcium chlorides and sulfates and magnesium, tend to precipitate when heated and can foul the tubes in steam and waste heat boilers. This fouling not only reduces heat transfer efficiency but also can lead to overheating and tube leaks, forcing unplanned boiler shutdowns. Hence, removal of these minerals is essential for efficient boiler and heater operation.