The valves are on Amazon for $2.99 for 2. Also the Nuk website sells them for around the same price.

My son uses these and I take them apart, run them through the dishwasher and have never had an issue. They're my favorite because they're so easy to clean.

Do you put tea in it? That's tye only thing I can come up with because tea molds quickly. .

I also soak dd cuos in clorox water and wash them, they have never looked like that and she has specific cups, water, juice and sometimes lemonade.

Buy the munchkin cleaning brush set and clean them really well after every use. Keep them separate until you use them too.

Buy a new one

My LO uses those sippy cups & that white insert has never looked like that unless he threw it somewhere & it wasn't washed in a week or something.

I would toss and get a new one. I've run through 10 or more sippy cups & I only have two right now. Smh

My lo uses those cups and they never get like that so I would just throw it away. Make sure if you get new ones to always take that white little piece of before washing it.

I always take them apart, rinse and throw them in the dish washer. Ive never had this problem .

I agree with the ladies I would trash it you don't want your LO getting sick.. I wash or soak (warm soapy water) my DD's cups every night, one every 2 days I sterilize them in boiling water for 5 minutes then let all the parts dry

I'd also like to add that I would trash that if it looked like that.

I soak everything in burning hot water and a tiny splash of bleach. Then I rinse everything and soak in just the hot water. Then I wash. This is a daily thing though. I start the soak, clean my living room, start the second soak, clean my kitchen, then I was everything. I also have a little bucket next to my sink that I leave everything soaking in all day. It seems like alot of work but it's really not.

I use to soak my nieces on vinegar then wash with bottle brush so they didn't get the gunk in the parts.

Do you leave it in all day long? We have like 10 of these (I have twins) and the only time we leave a regulator in all day is if it's only water. I wash their milk/juice out as soon as they're done drinking it.

A brush that cleans the nipples on a bottle should take care of that.

I have that same one and its never looked like that but then again we only put water in that sippy.

Buy new ones on amazon they come in packs of 2, and pick up a small bottle brush as well. We just scrub it with the small brush after each use and it hasn't been an issue.

Do you always tale the white part off? If you put fruit juice it happens by the end of the day

I do wash them everyday idk how they got like this ?

Yeah with my sons sippy i always wash it at the end of the day supper good i would just trash it if it got like that

They sell those white pieces on amazon but they are more than cups.

I soak mine in a gallon of hot water with one ounce of clorox and then boil piece afterward in water, then wash. It will clean them even after my dd hid a cup with milk in it for a week ???

OMG how did that even happen? We use these and this has never been an issue. I'd definitely throw them away. Next time soak them and lay them out to dry.

the cup and the cap are still good though. do you know if they sell the white piece separately or something?

or do I just have to buy all new cups every time this happens

I would trash it and buy a new one, maybe use the bottle brush attachment that has the little nipple brush, but this one I would trash. I hate these kind of cups, I'm so thankful Ds doesn't use these.

I would just trash it.