There can be many reasons why semen looks like water, including physiological reasons, as well as pathological reasons such as high frequency of ejaculation, oligospermia or azoospermia, and seminal vesiculitis. 1. Physiological liquefaction: When semen is first ejected from the body, it can solidify due to the presence of coagulase, and small jelly-like crystals can be seen under the naked eye. Usually, it can disappear gradually in about 30 minutes, the process is semen liquefaction. The naked eye can show that the semen becomes thin, like water, which is a normal physiological phenomenon. 2. High frequency of semen discharge: In daily life, if you have frequent sex, masturbation or spermatorrhea, too much semen is discharged, which can easily lead to semen becoming thin and watery. It is necessary to pay attention to it, quit bad habits and have regular sex. 3. Oligospermia or azoospermia: As the components in semen are mainly prostate fluid and urethral bulb fluid. If there are few or even no sperm, the semen can behave like water. 4. Infectious diseases: If you suffer from infectious diseases such as seminal vesiculitis, epididymitis, etc., it will affect sperm production and in vitro coagulation and other phenomena, resulting in semen becoming watery. There are many reasons why semen is like water, it is recommended to go to the hospital in time for semen analysis and further treatment after clear diagnosis.