Weather electric or gas heating could be expensive. The use of solar water heating will reduce the cost of energy used. It will reduce the amount of carbon dioxide that enters the atmosphere every year. It also helps to avoid nitrogen oxides, sulfur dioxide, carbon monoxide, and other pollutants that result when you use electricity, gas, propane, or another fuel source. Solar water heaters protect rivers, lakes, streams, and oceans from mercury and other pollution caused by power plants as well.