Oil, coal and gas are all every bit as natural as water. Some people have found a way of making a profit out of supplying it, that's all.
All of these things have to be treated to make them usable. In the case of oil, coal and gas especially they can only be got out of the ground by some fairly strenuous efforts with highly technical equipment and trained personnel; water is abundant but usually has to be treated by similarly technical means to make it safe to drink. The companies that do these things consider that they have to recoup their investments, I guess.