My DD did that too when she was about 7-8 months old for about four weeks from memory (bit of a blur now). Then she got gradually later again but it happened very gradually. Now she normally wakes between 7-7.30am and has sometimes been waking after 8am - just when I want her to start waking earlier as I'll be going back to work soon.

TBH, I didn't even think of giving her water, I just continued giving her a bottle on waking but she would always stay up for a couple of hours before going back to bed. I kind of just went with the flow.