Tips for locating the source of odor of well water include taking water samples at the wellhead, from an outdoor tap, from an indoor cold-water tap and from an indoor hot-water tap. The location at which the odor is first noticeable provides information about the source of the odor. Owners who are unable to locate and correct the source using this method can benefit from water testing.
If the odor is present at the wellhead, the likely source is in the well itself. In areas where water is high in sulfates, certain bacteria break down these chemicals to produce hydrogen sulfate gas. While these bacteria are harmless for consumption, the odor they produce is unpleasant. Options for treating the odor include periodically chlorinating the water to kill the bacteria or aerating the water with a large, nonpressurized tank to allow the gas and odor to dissipate.
If there is no odor at the wellhead, but it becomes apparent at the outside tap, old galvanized pipe is a likely cause. The pipe provides food for other odor causing bacteria. Similarly, water without odor at the outside tap that takes on an odor at the cold-water tap is likely due to galvanized pipe in the house. When the odor is only apparent in the hot water supply, it is usually due to a reaction with the anode rod in the water heater. Replacing the standard anode with an aluminum-zinc anode rod eliminates the odor.