I always use the hand wash setting in cold water only with wool/cashmere shampoo instead of detergent then lay flat to dry. I don't think I've ever taken cashmere to a dry cleaners. If your washing machine doesn't have a hand wash, gentle or wool setting then sink/tub washing the same way (cold water, gentle agitation) should be fine. It will just make the sweater quite heavy with water therefore a little trickier to work with but it can be done that way. Be sure to rinse out all the soap, don't twist or stretch the fabric out and reshape on a flat surface (perhaps put a towel down first) to dry.