use of definite article before "waste" and "costs"

Question

What is the correct use of the definite article for the following sentences:

1. The new procedure reduces THE waste.
2. The new procedure reduces waste.
3. The new procedure reduces THE costs.
4. The new procedure reduces costs.

Can you give a reason for the correct sentences?

Later edit:

From your answers (thank you!), the reasons for "the" are two:

• waste or costs are mentioned before

• waste or costs are NOT mentioned before, but it is expected that the kind of waste or costs is known

On the other hand, the reason for using the zero article is when the above reasons for the definite article can not be applied. Now, in the sentence "The new procedure reduces waste," is the waste bound to its general meaning, conveying a bad stuff? But in the context of this sentence, the "new procedure" is something specific, and therefore the waste is bound to this specific domain where the procedure activates. This contradicts the fact that the waste has a general meaning in that sentence. How do we solve it?

Answer 1

Although all four mean much the same thing, there are shades of meaning.

The new procedure reduces the waste.

-- There is a specific kind of waste in mind. That waste is being alluded to.

The new procedure reduces waste.

-- There is no specific kind of waste in mind.

Answer 2

All four are correct. Consider you have waste, and costs. And then you define a category describing the amount of waste and costs for the last month. Then when you discuss the category of Waste, you say "The Waste". Similarly for Costs.

Answer 3

The distinction between them is that the definite article refers to specific waste and specific cost that have been previously identified. The lack of an article in the other sentences is really an implied indefinite article, which allows it to refers to any waste or cost.