My mom just got a new bike! It's a Trek 7100 with a step through frame and 13.5" (she's very short). With her arthritis she can get on and off the bike easily. She's been riding, or mostly not riding, a mountain bike, and she was amazed at how fast she goes on her new hybrid, and how comfortable it is.

She has one problem, the frame doesn't permit a water bottle cage. I'd like to suggest some alternatives to her.
I'll mention the camelback, I think she can try out my dad's, but she might not like the way it makes the water taste, or having a sweaty back.

She found a bag that she was able to make work for her water bottle, for her first, 30 min ride.

Do jersey pockets hold onto a water bottle ok? She thought that might work, but I'm dubious.