Pericardial effusion is not related to drinking water, and drinking water does not cause pericardial effusion. There are many reasons for pericardial effusion, among which the common main ones include:

First, tuberculous pericarditis, where infection with Mycobacterium tuberculosis is one of the most common causes of pericardial effusion, often accompanied by symptoms such as fever in the late afternoon and night sweats, with the PPD test often showing a strong positive result.

Second, tumors, which are also a common cause of pericardial effusion, often accompanied by unexplained weight loss and other symptoms.

Third, heart failure, where patients with heart failure also often have pericardial effusion, with clinical symptoms including difficulty breathing, fatigue, and limb edema among other signs of heart failure, generally with a clear history of organic heart disease.