... a pretty remote one.
blood-borne diseases generally are not transmitted except by body fluid-to-body fluid exposure, i.e. sharing needles, unprotected sex ... taking this water by mouth which would probably have a miniscule amount of pathogens, if any at all, is a pretty low risk, although gross.
if you're involved with using IV drugs or other risky behaviors which I imagine you might be were you in this situation to begin with, it's definitely worth your time to get tested, if only for your peace of mind.
but catching anything this way is probably a distant possibility.