While pneumonia can lead to fluid building up in the lungs, water in the lungs is not a cause of pneumonia, according to Mayo Clinic and the American Lung Association. Viruses, bacteria, mycoplasmas, fungi and other infectious agents, and certain chemicals all potentially cause pneumonia.
Pneumonia is an umbrella term for a number of different types of infections that affect one or both lungs. Rather than being one single condition, pneumonia can result from a number of different causes. The treatment for each patient depends on the underlying cause. About 33 percent of pneumonia instances in the United States each year are the result of respiratory viruses, and these viruses cause more cases of pneumonia in young adults and children than any other source of infection, notes the American Lung Association.
Bacterial pneumonia can strike people at any age, and it develops on its own or after a bout with the flu or a cold. Respiratory diseases, viral infections, compromised immune systems and recent surgery are the greatest risk factors, reports the American Lung Association.
Viral pneumonia is an instance of a respiratory virus that ends up in the lungs rather than the upper respiratory tract. This type of pneumonia is often severe and even fatal at times. The virus sets up shop in the lungs and then multiplies, but even with this type, virtually no signs of fluid in the tissue appear. Some cases worsen when bacteria invade the lungs at the same time, states the American Lung Association.