If u had a 18.5L water in a plastic container, in a room that was at 144 degrees. How long would it take for 18.5L water to rise to that temperature? Im trying to buy a water storage device, but it cant go over 122 degrees.
If you put something in a room at 144 degrees it will eventually reach 144 degrees, it's just a matter of how long it takes. To work that out you need to know the thermal resistance between the room and the water. That will depend on the thickness of the plastic container, it's surface area and factors such as is the air or water stirred or subject to convection. It might well be easier to determine the thermal resistance experimentally.
You also need to know the starting temperature of the water. It would also make quite a difference if your units are Centigrade!