Water from refrigerator tastes bad after 5 day power outage

I am guessing that the rest of the house has no issues with smell or taste of the water. My first step would be to empty the ice tray and wash it really well with a mix of baking soda and water mixed into a paste. While the ice tray is out carefully check the ice unit for any evidence of mold or odors. Change the filter. Purge the system by making and throwing out a couple of trays of ice. Fill and dispose of a couple of gallons of water out of the dipenser.

In addition to mikes' advice, consider changing the prefilter for the line that feeds a refrigerator, if there is one.

1. The most common setup is a line that comes up through the floor from the basement or sideways from a kitchen sink.
2. A refrigerator line is either a thin plastic tube or a thin copper tube.
3. Trace where the line comes through the floor or the cabinet to the refrigerator.
4. Follow it back to where it attaches to a larger pipe.
5. See if there is a canister somewhere along that line. It would be about 3 inches across and 6 to 12 inches in length. That is a prefilter for the fridge.
6. If you find one, replace it also. Take it to a home center or plumbing supply store for a similar one. Brand is not an issue and there are pretty universal fittings to attach them.

I had problems with the taste of the water as well. When the line was originally installed they used a flexible metal line....had it changed to a clear plastic line and now the water tastes just fine...