Last time I used them there was a small charge for the washing powder but the amenities, machines and irons, were free.
If you are really particular about you tea I would take a supply of your favourite brand. regards Ida
Remember you will be on an American ship so the quality of tea is not always to British tases.
Going on the Grand Princess next year is there a self service laundrette on the ship. Also are tea coffee facilities in the cabins.