Fuelbelt bottles

I cleaned my Fuelbelt bottles last week. If you haven't done this, you might want to. I pulled them all apart and found all kinds of awesome black mould in the tops. Gross. Some I couldn't get totally clean. I soaked them in hot soapy water and they are still gross. Now the thought of drinking from them is making my stomach turn.

I'm trying to decide if I want to keep on trying to clean them or if I should just toss them and buy a new set. I've had them for 2 years after all...

If you have any cleaning suggestions, please feel free to post them.