No, the fluid cannot absorb water but you can get water in your
brake system and that would be bad. --Most brake fluids used today
are glycol-ether based. Glycol-ether brake fluids are hygroscopic
(water loving), which means they absorb moisture from the
atmosphere under normal humidity levels. Racing brake fluid may be
synthetic and not have this problem, but in the everyday world,
brake fluid does absorb water.