If you sue for water leakage upstairs, the property is obliged to provide the information of the upstairs owner. According to the "Regulations on Property Management", property service enterprises should provide corresponding services in accordance with the provisions of the property service contract. The realty service enterprise fails to perform the realty service contract, causing personal and property safety damage to the owner, and shall bear corresponding legal responsibilities according to law.
Therefore, if you sue the upstairs owner for water leakage, you can apply to the property management company and ask them to provide the information of the upstairs owner. If the property management company cannot provide relevant information, it can consider other ways to solve the dispute, such as contacting the local housing management department or lawyer for consultation.