During seasonal variations in our Water Treatment Plant's source water, we may get an increase in naturally occurring organisms that cause taste and odor problems. Although they are unpleasant to our noses, they are harmless.
If the water you draw from the tap smells but does not smell when you fill a glass and walk away from the faucet, the problem may be the sink.
Often times odors related to garbage disposals or "u traps" are the culprit. Food particles caught in the disposal will rot and give off odors. Also, dishwashers may be a cause of odor since they are plumbed in line with a sink and could be depositing food particles. If you suspect either to be the cause, an easy and efficient way to clean the disposal is to pour 1/2 cup of bleach (residents with septic tanks should not use bleach), vinegar, or baking soda with a couple of ice cubes. Run cold water and the disposal. This will dislodge and flush away any food particles.
If you suspect the dishwasher is the problem check by keeping the door to the dishwasher closed, smell the sink drain then open the dishwasher and smell inside of it. If the dishwasher is the source try doing a rinse cycle without dishes. Also, be sure to scrap and/or rinse dishes before loading the dishwasher or run more frequently to minimize the chance of food particles rotting.