Pneumonia is often described as people having water in their lungs. If you do drown or take in a huge amount of water through inhalation, you could develop pneumonia. However, not all pneumonia is due to water in the lungs, but is instead accumulation of fluid in the lungs, which may have nothing to do with inhaling water. The body can produce fluid in the lungs because of infection, high pulmonary pressure, as a result of surgery, and for a number of other reasons. This isn’t technically water but "fluid."

How people do get water in their lungs is usually very specific. You must inhale water (not a recommended practice). And don’t expect that water in the lungs will remain long, especially if you take in a very small amount. If you’re having a glass of water and you drink it and inhale at the same time, you may have that experience of water going down "the wrong pipe," as the expression goes. This generally induces significant coughing, since the lungs will reject the water, and do everything they can to push it back out of an environment where it shouldn't exist.

On the other hand, when people take in huge amounts of water in their lungs, such as if you drown, or even inhale about a teacup’s worth of water at once, it may effectively cut off oxygen supply and cause unconsciousness or death. When a person who has taken in water in their lungs and has stopped breathing, another person should perform mouth-to-mouth resuscitation in order to get the water out. When this works, most people will appear to vomit the water and then able to breathe normally, with some residual coughing. Drowning, however, is serious business, and doctors might want to evaluate a patient over the next few weeks to be sure that no infection to the lungs has occurred. Also, the longer the person has not been able to breathe, the more chance he or she has of brain damage, because the brain was deprived of oxygen.

Unfortunately, it is fairly easy for young children and inexperienced swimmers to get water in their lungs. Especially if panic sets in, respiration may increase and cause people to get water in their lungs quickly. Sadly, young children can drown not only in swimming or even wading pools, but also in bathtubs. Proper vigilance around inexperienced and even young trained swimmers and young kids bathing or wading is extremely important. Never leave them for a second. If you must leave, take the bathing, swimming or wading child with you.

Don't rely on safety devices to prevent children from getting water in their lungs. Especially things like arm fitting flotation devices or floating mattresses and inner tubes will not necessarily prevent a child from drowning. Arm fitting flotation devices are fine if the child is being closely watched at all times, but a child can lie on his or her back with these on, and water could rush over their heads, causing drowning. Even life jackets are not always a safe enough measure to prevent drowning. Constant vigilance is always better.

Children are especially at risk for drowning from small amounts of water in the lungs because of their small lung capacity. It is easier to fill lungs with water and cut off oxygen supply much more quickly. It cannot be stressed enough how important it is for children to receive attentive supervision at all times, even if they know how to swim.