I took the car out for a about 30 minutes last night. I did push it a little hard. But this morning I come out and there’s a big puddle of dried coolant on the ground. I popped the hood and there’s coolant dripping out of the 2nd hose on the reservoir. So I’m confused as to what happened and how to fix it
While you were driving, was there any indication of overheating? In other words, did you smell anything unusual, and/or was there any indication of overheating (warning light or spiked temperature gauge) on your instrument panel?
It appears that your serpentine belt is new. If the tensioner wasn’t replaced, it is possible that the belt is slipping, and that can lead to an overheat condition. So, it might be worthwhile to check the tensioner.
If there was no indication of overheating, then my next suspect would be a breached head gasket. When a head gasket is breached, it can lead to greatly increased pressure in the cooling system as exhaust gases are driven into the coolant.
Have your mechanic check for evidence of a breached head gasket.
I see you don’t have a pressure cap on the reservoir, so the radiator must have a pressure cap.
Replace the radiator cap to see it prevents the reservoir from over-filling.
The rusty water leaking from the reservoir suggests that the cooling system has been very low for some time, the lack of coolant (use of plain water) and air in the cooling system promotes rust. Driven long enough with the cooling system low will damage the head gasket.