Then you need to pressure test the system to confirm as it could be either that or a head gasket. The water pump drain is also there in case the water pump is the leak. That is why you need to pressure test the system.
I attached 2 YouTube videos for you to view as well.
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.