If you can see the sludge, then loosen it with a stiff brush and then rinse good.

The kitchen sink that has a garbage disposal installed also can develop a bad smell. A good soak with vinegar is recommended. Let it soak then turn on the disposal with warm water or hot. If the smell persists, then try baking soda and make a thick solution with warm water and soak in the disposal.

Often, if the smell persists, the rubber under the top entry hole has gotten coated with sludge and debris. The remedy is to turn off and disconnect the electricity from the unit. Use a stiff brush or cleansing scrubbing piece, some comet and scrub the black flaps. This will go a long way toward eliminating the smell.

If you have a sewer type odor in your basement sink area, it is likely that the basement floor drain trap is dry. All drains to a sewer system have a `P' shaped trap that is usually filled with water. This trap forms a barrier to keep the sewer smell out of the home. The water forms a type of seal.

If the basement floor drain is rarely used, then the water can evaporate. Ultimately the seal is gone and the sewer gas smell comes into the basement. The remedy is to add water to that drain regularly, the seal will be restored.

If none of these cures work, there may be a small leak around the base of a toilet or other fixture. Check for loose fittings. Probably a plumber will have the answers you do not. A was piece in a toilet can wear out; Some times there are some small holes in vent piping.

If there is a hole in the top of the horizontal piping beneath the floors, the odor may leak through even though no liquid did. The pipes made of copper; steel and cast iron can get these rusty areas.

If the smell of urine or sewer persists around a toilet, then the wax can be replaced. If the wax ring has been bad for quite a while, it is possible that the floor itself will need to be rebuilt.

A way to test the toilet is to grab it and try to rock it a little. If it does move, then the wax ring is probably bad and needs replaced. It is recommended that a plumber do this replacement since it is difficult to properly secure a toilet and match the toilet and the flange.

Sometimes there is a rotten egg smell coming to the sink nearest to the hot water heater. Inside the heater is a sacrificial anode rod. This rod is made of magnesium. It helps protect the tank lining from corrosion. When this rod goes bad, the magnesium gives off electrons that help sulfate produce bacteria. Removing the rod may resolve this problem.

It may also require you to turn the tank temperature up to 140 degrees for 8 hours. This higher temperature will kill bacteria from the water heater.

NOTE: make sure your water heater has a functioning temperature and pressure relief valve. Also warn the users in the home about this extra hot water. Keep children away from sinks and bathtubs at this time to protect them from burns.

This is how to clean a smelly sink. With this information it should be easier to keep your sink smelling good and fresh.