Leukorrhea that is like water is most commonly caused by the following reasons: First, bacterial vaginosis, which is caused by inflammation of the mucous membrane resulting in thin secretions and a relatively large amount, often accompanied by a fishy smell of secretions. Secondly, cervical cancer, endometrial cancer and fallopian tube cancer can all cause leucorrhea to increase like water. In this case, a comprehensive analysis must be given with clinical history, and if necessary, routine leucorrhea examination, cervical cancer screening and ultrasound examination are recommended to understand whether there are cervical epithelial lesions and cervical cancer, to understand whether there is abnormal thickening of the endometrium, and to do diagnostic scraping if necessary. If the leucorrhea appears like water during pregnancy, this condition is most likely caused by premature rupture of fetal membranes and it is recommended to go to the hospital for examination.