Punto 55S loses a lot of cooling water

Hi together, I drive a Fiat Punto 55S, built in 1996, 59800km. I have problems with the cooling water at the moment. Two weeks ago I filled up the tank again because the stand was below minimum. Yesterday I checked and the stand was back at minimum. Then I replenished yesterday. When I looked this morning, about 0.5cm cooling water was less present and when I drove then 50km I looked again and noticed the now almost 1.5cm cooling water was missing, ifw My first guesses were the cooler, the cooling water hoses and the cylinder head gasket. The cooler seems to be fine, I don’t see any wet spots, the hoses are not wet either and it probably won’t be on the cylinder head gasket either, because I don’t have any power or oil loss and I don’t see any white smoke (condensation water) coming out of the exhaust. What can it be? G Rute Skaarj