Boiling a DivaCup takes about 5 to 10 minutes in a regular pot of water on your stove. It’s the simplest way to sanitize your cup between cycles, and the medical-grade silicone can handle it without any damage. Here’s exactly how to do it, plus tips for avoiding common mistakes.
Step-by-Step Boiling Instructions
Fill a pot with enough water that your cup can float freely without sitting on the bottom. Bring the water to a rolling boil, then place the cup in. Let it boil for 5 to 10 minutes, but no longer than 10. Remove it with tongs or a slotted spoon and set it on a clean towel to air dry.
Before boiling, always rinse your cup with warm water and a mild, unscented soap. The goal of boiling is sanitizing, not cleaning. You’re killing bacteria that soap alone might miss, so the cup should already be free of visible residue before it goes into the pot.
When to Boil Your Cup
Boil your cup in two situations: before using it for the very first time, and at the end of each period before you store it. During your period, a simple rinse with warm water (or water and mild soap) each time you empty it is enough. Save the boiling for the post-cycle deep sanitize.
Protecting the Cup From the Hot Pot
The biggest risk during boiling is the cup sinking to the bottom and pressing against the hot metal. Prolonged contact with the pot’s surface can scorch or warp the silicone, even if the water is still boiling around it. A popular trick is to place the cup inside a metal whisk before dropping it into the water. The whisk cage holds the cup suspended in the middle of the pot, surrounded by water on all sides, so it never touches the bottom.
If you don’t have a whisk, just use plenty of water and stir occasionally to keep the cup floating. Stay nearby so you can check on it and make sure the water doesn’t boil off.
Do You Need a Dedicated Pot?
No. As long as you’ve washed your cup with soap before boiling, you’re putting a clean object into clean water. The boiling itself sanitizes both the cup and the pot. Wash the pot with regular dish soap afterward and it’s perfectly safe to cook with again. Many cup users skip a dedicated pot entirely without any hygiene issues.
That said, if sharing a kitchen makes you self-conscious about it, a small dedicated pot is cheap and easy to stash. It’s a comfort choice, not a safety requirement.
Why Boiling Won’t Damage the Silicone
Medical-grade silicone can withstand continuous temperatures up to 230°C (446°F) and doesn’t begin to break down until above 300°C (572°F). Boiling water tops out at 100°C (212°F), well within the safe range. You could boil your cup every single cycle for years without affecting its flexibility or structure.
The exception is if the water boils away completely while your cup is still on the stove. Direct contact with a dry, heated pot can reach temperatures far above 100°C and will damage the silicone. If this happens, inspect the cup carefully for warping, stickiness, a chalky texture, or any change in flexibility. If the material feels or looks different in any way, replace the cup.
The Microwave Alternative
If you’d rather skip the stove, you can sanitize your cup in a microwave. Place it in a microwave-safe mug or a purpose-built sterilizing container, add enough water to fully submerge the cup, and microwave for 3 to 5 minutes at 750 to 900 watts. The water needs to reach a full boil inside the container, so check that it’s actually bubbling before you start your timer. Some brands sell dedicated microwave sterilizing cups designed for exactly this.
Dealing With Hard Water Film
If your cup comes out of the pot with a white, chalky film that won’t wipe off, hard water minerals are the culprit. This is cosmetic, not dangerous, but it can make the silicone feel rough. Adding a small splash of white vinegar to the boiling water prevents the buildup. If the film is already there, soaking the cup in a mixture of water and vinegar for a few minutes will dissolve it.
Cold Water Sterilization
When boiling isn’t practical (traveling, no stove access), sterilizing tablets designed for medical or baby products work as a no-heat alternative. Dissolve one tablet in about 60 ml of cold water, submerge your cup, and let it soak for 15 minutes. Rinse thoroughly afterward. This won’t replace boiling as your regular routine, but it’s a solid backup when you’re away from a kitchen.