Dirty mouthpiece in reusable water bottles!

[cokezero26]

I clean my reusable water bottle regularly, especially the mouthpiece as horrible black dirt builds up inside it.
However, some of this dirt seems to have gone ‘in’ to the rubber part, if that makes sense? No matter how much I scrub and scrub it doesn’t come out!
I’m contemplating getting a new one purely because of it :(

Soak it overnight in Milton - that'll get it clean.

It's mold. Miltin or bleach

I have bleach, would that do?
I don’t have Milton but can see if Tesco has any tomorrow

Yes, you can use a splash of bleach
I do this( topped up with water) to remove tea stains on mugs