Both your refrigerator and dishwasher can get smelly if you don't keep them clean, but the odor is usually the musty one produced by mold. Sulfur smells come from hydrogen sulfide, and the anaerobic bacteria that produce it live in water or in the sewer. If you detect rotten egg smells in the kitchen, the cause could be contaminated water in the dishwasher or refrigerator, poor dishwasher drainage or an improper dishwasher drainage connection.
Rotten Eggs in the Dishwasher
Most dishwashers have a strainer that collects debris from dirty dishes and prevents it from clogging the drain. If you don't remove this screen regularly and clean it, the decomposing debris can produce an odor that resembles rotten eggs.
The Drain Hose
The dishwasher drain hose may be improperly installed, and this can lead to sulfur odors in two ways:
- The hose may be connected to the kitchen drain pipe after the P-trap instead of before it. This configuration provides no protection against sewer gases; they can waft unhindered directly from the sewer to the dishwasher drain and into the kitchen. The solution is to disconnect the drain hose and connect it properly to the sink tailpiece.
- The installer may have neglected to make a high loop on the hose. Most plumbing codes require this loop to be as high as possible -- usually to the underside of the sink counter -- to prevent backwash from the sink drain collecting inside the hose and putrifying. The solution is to loop the hose as required, but check first with your local building department. Your municipality may also require you to install an air gap on the sink deck and connect the hose to that.
If you smell sewer gases from the sink as well as the dishwasher, a vent blockage may have emptied the P-trap. If this has happened, you'll probably notice that the drain and dishwasher drain slowly -- they may even back up. You can usually fix this by clearing debris from the roof vent stack.
Rotten Eggs in the Refrigerator
Your refrigerator doesn't have any drains to worry about, so if you detect rotten egg smells, they must must be coming from the water. You may notice the odors in the dispenser water, the ice cubes or both.
The odor-causing bacteria could be in the water supply, and if so, you'll notice the smells in water from other faucets and fixtures -- including the dishwasher. If so, of the problem depends on whether you have a well or use municipal water.
You can usually eliminate an odor that you detect only in the refrigerator by the refrigerator water lines and replacing the water filter. If the smell is in the ice cubes, discard all the ice in the tray, wash the tray with a 50-50-solution of vinegar and water to disinfect it, and refill it. Discard those ice cube,s if they still smell, and refill the tray once more. The ice cubes in the second filling should be odor-free.