Water trucks do not spray public asphalt roads
Doing so makes mud on top of asphalt which is dangerously slippery
They only spray the construction site
They use power brooms and other equipment to clean roads

I would say he hosed you down on purpose and even if he didn't
I don't go for the no harm no foul train of thought
You could have been badly hurt by his "not seeing you"

His boss needs to know about this incident whether it was intentional or not
What's this jerk going to do the next time he's not paying attention or get's mad. Whichever the case may be.
Run you or someone else over with that truck that weigh's 40.000 pounds

Then claim he didn't see anybody

Maimed/Dead is fairly permanent as far as I know