My guinea pig bites at the sipper tube of her water bottle,

Animals all have personality quirks, and your guinea pig simply may not be comfortable with the kind of water bottle she has. It's important that she gets plenty of water, though, so you should try giving her a few options to see what she likes best. First, you can try putting her water bottle down a little lower; she simply may not be able to reach it. If that doesn't work, try using a smaller water bottle with a smaller tube, such as a tube designed for hamsters and gerbils. You could also try using a large tube, like the tubes used for rabbits. It may just be that you need to find the right sized tube for her mouth.

If none of those ideas work, you could try a heavy, hard-to-tip ceramic water bowl. These bowls make a lot more mess than water bottles, so you'll need to clean her cage more often to make sure her feet stay dry and clean.

If you try all these options and your guinea pig still doesn't seem to be drinking, you can take her to your veterinarian for an examination.