Water in the lungs may be pleural effusion. Diseases that can lead to pleural effusion include the following: 1. lung tumors, patients with lung tumors can have pleural effusion, accompanied by clinical manifestations such as cough, sputum, fever, chest pain and wasting, etc. The diagnosis can be clarified through bronchoscopy, puncture biopsy and sputum examination of cancer cells. 2.Severe pneumonia stimulating the pleura can lead to pleural effusion next to pneumonia, which can be clearly diagnosed by improving blood routine, C-reactive protein, lung CT and other related examinations. After the diagnosis of tuberculosis, anti-tuberculosis treatment is needed.