I rinse mine then let them soak in Milton (baby bottle sterilising tablets, less than £2 for pack of 28, they sell in liquid form too but the tablets are cheaper and do same job) overnight, it's always worked for me and I've never had anything damaged from it, there's no need to rinse after taking them out of soak if you don't wish as baby bottles can be used immediately after coming out of soak so I think it's pretty safe!