Soapy water wash definitely does not sterilize them; I just figure by doing that and the boiled water rinse and drying it right away that I've done a decent job of preventing anything from taking root and growing in the device. Given that the drug travels through it pretty quickly compared to all the breathing in/out with nebulizers, I tell myself not to worry about it. Heck, my son probably puts more germs up his nose with his finger than will ever grow in his aerochamber and nebulizer.