Not sure how many washes you get out of the bottle, it's a big bottle but you have to put it on dry hair so you do use quite a lot. I've used mine twice (probably using about 16-20 pumps) and it is still really full. I haven't had any staining, it does change colour but the water runs clear(ish) when you rinse it out. I use light brown but the darker colours may be different.