My left lung has water is that bad?

Maybe not terrible: If by "water" you mean fluid around the lung (called pleural effusion)- this has many potential causes. The suspected cause depends on your individual health history. At your age the most common cause of fluid next to the lung is an impairment of cardiac output, resulting in increased pressures in lung/chest blood vessels.

Lung issues...: When there is fluid in the lungs it could be associated to various conditions. One of them could be a pneumonia in which case fluid accumulates due to inflammation in the area. Also people that suffer of heart failure may have backflow of fluid and it accumulates in the lungs. In some cases if there is a tumor fluid can be found around it. These are some of the few issues associated w/ lung fluid.

Yes: In the lung is pneumonia or congestive failure! around the lung is a pleural space collection- effusion.