I just accidently gave my 10 month old DC day old water and I'm feeling very guilty!
She has a couple of identical sippy cups and I was out yesterday evening so wasn't here to wash it out/sterilise and her DF must have put a seperate one in the steriliser. I made a new one this morning but have now found the one I made and realised I have given her the old one from yesterday morning all afternoon 
It was boiled water in a sterilised cup so I am hoping it will be okay but I am worrying a bit, anyone with any experience/knowledge on the risks??