How long does it take milk to spoil at 20 degrees in 1 day?

At 20 degrees Celsius (68 degrees Fahrenheit), milk can begin to spoil within a few hours due to the growth of bacteria. Generally, it can remain safe for consumption for about 2-3 hours, but after 24 hours, it is likely to be significantly spoiled and unsafe to drink. Factors like the initial freshness of the milk and exposure to contaminants can also affect spoilage rates. It's best to refrigerate milk to prolong its shelf life.