Stop being cheap and buy new ones . My sport is worth $5 for a new bottle

If I had dishes that did not come clean after being washed with bleach and put through the dishwasher, I would certainly get new ones!

If he was cleaning with bleach, the problem wouldn't exist... therefore, new bottles aren't the answer. A lesson from mother about cleaning them is.

Not if it litters the countryside affecting wildlife and peoples enjoyment it isnt right no and thats just laziness.

If you're finished with it put it in your bag when you use another one.

Three options only:
disassemble and clean with brush and bleach etc - will grow again soon,
or don't worry - what does not kill you makes you stronger,
or dump and get new bottles

Besides, mold tastes good!

There exist tablets that will take care of it. I used to have them even though I would not know where to buy them from. My girlfriend has a Sigg bottle that came with similar tablets. They do the job of keeping everything clean, though you probably want to use them before there is any visible mold.

Another thing, that is more about prevention, is that it is best to not let water sit in the bottles after a ride. After a ride, I take the bottle from the bike, rinse it and leave it open without the cap on so it can dry.

I use a mild bleach solution in the bottles, and the camelback. If you rinse it out well, it works fine.

Milton Antibacterial Solution - not tested on animals. Babies on the other hand...

It's a baby bottle cleaner found in the baby supplies aisle of the supermarket. Fill bucket with water and a splash of the solution. Leave bottles submerged overnight and then remove and rinse them in the morning.

Water bottles washed in the dishwasher is just a lazy feel-good, not a real cleaning. Being lazy and liking to feel good, I resort to the dishwasher. But just think about how the dishwasher works - spraying water around. A bottle brush and some hot soapy water is going to work much better. Once you have mold, however, you're going to need bleach to knock it out if you don't like your biology experiment.

I've had major growth inside my Camelbak spout due to heavy use of electrolyte drinks, dissambled the thing and cleaned with mild soap, water and old toothbrush. Instead of leaving to dry outside I've stuck 'em inside the Freezer, not fridge..no molds since then

Ah... mold, a great antibiotic!