yes u need to wash it if you use anythink other than water ,even then a good rinse is always a good idea ,id use bicarb of soda to get your mold out
use hot water not boiling and put bicarb in first then add hot water .Swish arround and rinse well ,may need a few goes
when eva you store it leave cap off so it can breath ,if you get a horrid taste in it like rubber taste ,use salt and vinegar to flush out a few times should get rid of the rubber taste
cheers