I thought the bottles were bigger when I bought it. They're about 18 oz. You put the soap in first, then the water. The indicator lines say I should put more water in, and it's overflowing. I almost recommended filling the water first, but that's not a fix as you have to physically attach the bottle to the refill to get it inside. And it's not exactly fast either. I am going to buy the refills so I can waste "less" plastic, but I am going to be watching out for the cost. Right now ar Walmart, yoSee full review