Your baby
does need some water, but she wouldn't be taking that much from you anyway, as she's breastfed. My LO took a while to get used to her sippy cup and didn't take a really good drink for a while. Remember she will get a lot of 'fluids' from your milk.
Are you certain she is dehydrated? Does she seem listless? Dry mouth or dry eyes? Are her nappies dry?
Another way of getting more water down her, I suppose, would be to add more to her purees. That would be a bit of a step back though, as by this point you might be trying to make the purees a little thicker. But then, you have the additional problem of her not being interested in food.
Are you taking her off the breast to then give her solids? How are you combining the breastfeeding and solids? I'm asking as I wonder if she feels 'deprived' of the full breastfeeds she is accustomed to.
Take it slowly, and try not so show her that you are concerned. Stick a bib on her before you put her on. Give her her milk, then, while she is still on your knee, dip a clean finger into her puree and rub it into her mouth. Make sure you are grinning and smiling and whoop and cheer if she accepts the taste. If she doesn't, just pop her back on for a bit and try again a short while later. If she still isn't interested, don't stress and let her finish her bfeed without disturbance. Prepare to be covered in food, and don't bother with wipes or anything until she's completely done eating.
Try and change the 'dinner time' routine to something that is close and fun and positive. Perhaps having granny give her her solids with a clean finger while you offer the breast anyways, so there is no pressure. Then granny can whoop with delight and clap too when she takes it. You would be amazed how early babies respond to praise, and how keen they are to please you. Change that bowl and spoon she hates so much for a bit - perhaps just use normal bowls that she sees you using all the time? And as I said, ditch the spoon for now. Also, you could sit ans eat a banana or similar while she is next to you, at a time when you would expect her to be hungry, and half way through it, put the banana in her hands. She might explore it a little with her mouth. She might not. Either way, don't thrust it into her mouth, let her be the one that rams it so far in her gob you're left panicking she'll choke...(she won't, she'll just moosh it up with her wee solid gums - see 'isabellasmum' for advice on baby led weaning

).
I hope this helps. Let us know how you get on xxx