Rainbow puddles are not rainbows.
If you see a shimmery puddle, often green, on the street don’t let pup drink from it. It is probably antifreeze which is poisonous.
Antifreeze is generally ethylene glycol which lowers the freezing temperature of the water running through a car's engine, but it is both highly toxic and very sweet. And dogs love sweet.
If, despite your best efforts pup does get a few slurps, immediately call ASPCA's Poison Control Center. They will ask you to estimate how much pup drank, ask how large he is and some other questions to help you determine your next steps.
Remember Safety Tip #1? You should have that phone number on your Pet Emergency Page in your smartphone. (888) 426-4435.