Two different questions
Hydration is part of general wellbeing. The National Eye Institute describes common floaters as shadows from changes within the vitreous; it does not identify drinking more water as a treatment for them. Do not assume new floaters are simply dehydration.
When to get help
A sudden increase in floaters, flashes, or a curtain-like shadow calls for urgent eye care. For persistent, stable floaters, an examination can help establish the cause and the options relevant to you.