My parents babysat DD today and I left with them a formula bottle + backup water bottle in case we were going to stay for dinner and she needed more then one bottle. I gave them instructions on how to make the formula bottle up if the needed it however they didn't listen and fed her about 90mls of water...

Is that ok for her to have as a once off thing? She was asleep when we got there and was really hungry when we got home so feed her a full bottle again. I am just worried it might of hurt her

Thanks