So (adj) that - object repetition

[morecoffee]

In a sentence such as

"The coffee is so hot that I cannot drink it."

Is the "it" at the end neccessary?

I don't see any grammar rules specifying that it should be, but it does sound wrong to me to say:

"The coffee is so hot that I cannot drink."

Thanks.

[Barb_D]

Yes, you need the "it."

The coffee is too hot to drink.
The coffee is so hot that I cannot drink it.