If the chambers of a down jacket soak up with water, the down clumps and the insulating effect is lost. So, think twice about whether your down jacket actually needs to be washed. As a rule, you have only worn them for short periods of time and without direct skin contact. Extensive ventilation should therefore normally be sufficient. If that's not enough for you, you should definitely follow the instructions on the care label. If anything is unclear, they will help you in the store, on the manufacturer's website or in the cleaning department.