Water can have various odors, including: A rotten egg smell, which indicates the presence of hydrogen sulfide. If it's only hot water, replace your water heater's anode rod. If it's your entire water supply, install an iron filter. A chlorine-like smell, which is likely due to chlorine disinfectant. A carbon filtration system will help. A musty odor, which is caused by organic matter. Install a reverse osmosis system for more pleasant-smelling drinking water. These smells can result from natural sources, bacteria growth, or chemical treatments in the water supply.