Measure 1/2 cup of baking soda and pour it directly down your sink's drain. Let the baking soda sit in the drain for at least 10 minutes, then run your hot water. Baking soda helps to clean, disinfect and deodorize fouls smells and is safe enough to use on your drain. Baking soda can also be used to clean the sink area as well, including the faucet.
White distilled vinegar has a strong odor by itself, but it eliminates odors safely and effectively while killing mold, bacteria and germs. Pour a cup of distilled vinegar down your drain. You may need to leave the camper for a while if the vinegar smell is too strong, but the odor will dissipate after a while and leave your sink clean and smelling fresher. Combine 1 cup of baking soda with 1 cup of hot vinegar to maximize the results, then allow the combination to sit for five minutes before flushing the drain with hot water.
Place a pan directly under your p-trap, then twist the p-trap joint counter clockwise in order to unscrew it. There are normally two joints on a p-trap, and once you unscrew the first one, you will able to unscrew the last one. Pull the curved p-trap pipe out. Use a pipe cleaning brush to scrub and push out any decayed food and gunk that's trapped. Sprinkle some baking soda in the p-trap, allow it remain in there for a few minutes, then flush it out with hot water. When you are finished, put the p-trap back into place and screw the joints back into place.
Create a pleasant aroma by squeezing a few tablespoons of fresh lemon juice directly into the drain. Lemon juice will not only leave behind a delectable smell, but the acids in lemons also help to to effectively eliminate bacteria. Let the lemon juice sit in the drain for a few minutes, then flush with hot water.