Generally, this smell is coming from the drain and not the water. The odor is probably coming from a drain with materials such as food or hair stuck to the walls of the drain pipe. If you have been away for a few days, you may just need to flush out the line by running the water for a couple minutes. To get rid of the odor, you can pour about a half cup of bleach down the drain. You will need to do this at every sink with the odor.