Identification

• White crusty mineral deposits are caused by water vapor coming through the floor. This is most often caused by soils saturated with water and high water tables. Once moisture begins to seep through the bathroom floor, it creates dampness and leaves behind mineral deposits that are easily seen on the floor surface. The appearance of these deposits depends on the rate of water evaporation and the amounts of sodium, magnesium, calcium, carbonate, sulfate and chloride they contain, according to North Dakota State University.
  
  

Effects

• Mineral deposits on bathroom floors may appear white in color and have a fluffy or moldy texture. These deposits may also be visible in damp basements where moisture is abundant. Mineral deposits are not harmful to humans, but these substances may corrode floors in bathrooms and basements over time. It is often difficult to determine if these deposits are harmless minerals or if they are damaging mold growth. Mineral deposits do not have an odor, while mold growth smells musty or foul.
  
  

Diagnosis

• Homeowners must determine if the white crusty deposits in their bathrooms are caused by mold growth or from water vapor. Mineral deposits cannot be removed simply by placing water on them. Scrubbing the area with an acidic solution such as vinegar will remove them effectively. If you can't remove white deposits with vinegar, then the growth may be caused by mold.
  
  

Solution

• Promoting proper drainage is key to reducing water vapor and mineral deposits on bathroom floors. Homeowners can prevent this from occurring by installing a proper drainage system around the home's foundation that helps remove excess water quickly. If these deposits are not easily removed with vinegar, you may want to consult a mold removal specialist for advice. Reducing the humidity in your bathroom will also help prevent mold growth. Installing proper ventilation fans and using mold killing cleaning products will help prevent the development of mold.