I think I found the reason for the water leak. This has nothing to do with the original topic, but maybe good to know, anyway.
There is a hole in the bearing housing of the water pump shaft. If the pump shaft oil seal brakes, water goes in the bearing housing and comes out through the hole.
Here you can see the hole on the right side of the pic, and the water pump shaft on top of the cylinder head.
The head gasket does not block the hole, only half of it, as you can see from the mark on the gasket.
If there was no such hole, all water would mix with oil when the water pump shaft oil seal brakes.
Ripa