Decaying organic matter can cause water to develop a rotten-egg smell. This smell is caused by hydrogen sulfide, a by-product of organic decay. It's important to keep your plant base clean to prevent this smell from developing.
Causes of Hydrogen Sulfide
Decaying vegetation or chemical reactions with certain minerals can lead to a smell like rotten eggs. As water moves through potting soil, it comes into contact with these minerals or dead pieces of vegetation.
Hazards of Hydrogen Sulfide
Hydrogen sulfide is considered to be a hazardous gas. If you begin to notice the smell of rotten egg coming from your plant, open a window to vent the fumes. Even with low exposure to the gas, it can still irritate the eyes, nose, throat and respiratory system. If the smell persists or you exhibit symptoms, discard the plant immediately.
Removing the Smell
To remove the smell of hydrogen sulfide, it's important to keep the potting soil clear of dead leaves and other debris. Pick out leaves from the base of the plant at least once a week. You should also remove stagnant water in the base of the drip pan every day.