Adult navel scarring and yellow water is considered to be umbilical infection, the cause of which may be related to bacterial infection, poor hygiene, trauma to the navel and other factors. 1. Bacterial infection: the common pathogen is Staphylococcus aureus, if Staphylococcus aureus invades the skin of the umbilicus, it may lead to localized umbilical cord infection, which in turn triggers the umbilicus to have a scar and flow of yellow water. 2. Poor hygiene: If the adult hygiene is poor, or daily ignore the umbilical cleaning, may make the bacteria attached to the local skin, which may induce navel infection. 3. Trauma to the navel: if adults often scratch and pick at the umbilicus, it may lead to damage to the umbilicus and infection with bacteria, which may induce navel infection. The causes of umbilical infection are not one and the patient is advised to seek medical checkups to clarify the cause and get timely treatment.