water spots suck! if you don't get them off soon enough, the mineral deposits cake onto your paint and you have to use a mild acidic wash with vinegar to rinse them off.
whenever i come into contact with stupid sprinklers while driving, i make a note to spot wash the areas with a microfiber and wet rag to prevent water spots.
in your case, i would recommend a water-proof car cover or a thicker brand of wax to help protect against those deposits.
i HATE HATE HATE sprinklers for this reason. the area i live in is always windy and even if you are not close to the sprinklers the wind will blow a neighbor's sprinkler water over to you and mist your car
2011 Mustang GT 5.0 Coupe/Brembos/3.73
"I'm also 6'5" and 270 lbs. and could crush a person's bones with my bare hands"