First check the Marmot care label. If it says you can, then you can. The fear of using powdered detergents is an old one. Detergent will not strip the water repellant treatment from the garment, however, if it is not rinsed out properly the detergent residue will 'cover it'.

Liquid detergents were also a no no because they contained more 'surfacants'. They are designed to break water tension to help with cleaning. however, this means water will not bead on the outside of your jacket. Liquid detergents now contain less surfacants but as there are so many different brands out there, it is best to play it safe and stick with powdered detergents.

It is also fine to use cleaning products designed specifically for technical outdoor clothing such as those made by Grangers.