Formula milk accidentally add 10ml water more ...

Hi,I accidentally add 10ml water (pour from new flask,hard to control the pouring) more each day to bb ( turning 3mths) formula milk during each feed,almost few weeks.... Just saw online article is harmful for bb,will it harm my baby?now I stop doing it already after seeing article. :( So far bb no issues and no signs of sickness... I felt like a bad mother.