Since the ninth century, the word that has been one of the most frequently used words in the English language. It functions as pronoun, adjective, adverb and conjunction.
A browser search for “that” brings up 14,490,000,000 hits.
Small wonder so many copy editors do their best to stamp out that whenever possible.
One editor tells his authors to search their manuscript for all uses of the word that and then “Evaluate each and delete 95 percent with no loss of meaning.”
I’d say 95 percent is a bit high, but writers can reduce the number in a great many instances without loss of meaning. On the other hand, that should not be purged blindly in a misguided effort to save words.
The following statement by a police spokesman quoted in a newspaper account illustrates the natural use of that in spoken English:
We have to make sure that there is nobody inside any house; there’s always the potential that our suspects have fled into a house that was occupied, which is why it’s highly important to us to make sure that’s not the case.
Four thats occur in the sentence above:
1. As a conjunction introducing a noun clause that is the direct object of “to make sure.”