Can you wash the nipples and plastics parts in the dish washer?

Yes, but you have to take precautions. Due to their light weight, they tend to get washed out of place, and wind up melted in the bottom on the heating element. You can buy baskets with lids designed just for this purpose in most baby departments. I have seen them at Target, Wal-Mart, and Babies R Us, and they are only a few dollars. Even then, check the nipples after they are washed to make sure no debris managed to get dried on or in them.