We recommend at the end of each cycle; the DIVA Cup may be submerged in an open pan of boiling water (continuous rolling boil) for 5-10 minutes. Do not leave the boiling pot unattended and use enough water so that the pan does not boil dry. Please know that boiling is not “mandatory”, it’s just a recommendation. Some consumers do not boil their cups at all, as regular cleansing with soap and water can be sufficient to maintain the integrity of the silicone.