There are certain places where you don't mind smelling stagnant water, like when you come across a pond covered in lily pads, surrounded by moss-covered rocks. If your bathroom smells like stagnant water, it is a warning that you have a fungus problem in that room.
If your bathroom has a smell like stagnant water in it, you'll notice the odor in one of two ways. The first is catching the scent whenever you are near the sink or shower drain. The smell will be less intense after you run water into the drain, but it always returns. The second way is if the odor is present all the time and you can't get rid of it by opening a window, running water or turning on the exhaust fan.
The cause of the stagnant smell is mold or mildew growing in your bathroom. These fungal growths thrive in the moist environment of a bathroom. They can grow inside the drains of sinks and showers. They can grow just about everywhere else in the room too: on tile, on towels on the walls and even the ceiling. In addition to making your bathroom smell musty , mold and mildew release spores into the air that can cause health problems in your family members. Reactions to mold exposure include headache, itching eyes and coughing.
Getting rid of the fungus will get rid of the smell, too. For a stagnant smell in a drain, pour in 1/2 cup of baking powder to deodorize the opening and the pipe. Wait 15 minutes, then pour in 1 cup hydrogen peroxide to kill the fungus. Let it sit for an hour before running water into the drain. To get rid of mold growing on other bathroom surfaces, mix 1/2 cup of bleach and 1 gallon of water. Using a sponge, wash away all mold and mildew. Use a fan to dry the cleaned surface as quickly as possible.
You can prevent mold and the smell of stagnant water from returning to your home by reducing the moisture level in the room. Run an exhaust fan during and after every shower, or open a window to release the steamy air. If mold is growing on a patch larger than one foot square, contact a mold remediation specialist. This much mold needs to be cleared by a professional to make sure it hasn't spread anywhere else and to ensure all damage is found.