Of course it will. Don't directions say to just add water? You can also make buttermilk by adding 1 tbs lemon juice to milk and let curdle a few minutes. No problem. I can remember a thousand years ago when I came home for summer break from college, I was dating a guy from NY state. He stayed with us for the weekend and Mama told him where the coffeepot was. Milk is in the fridge. He came back and sat for a few minutes with the weirdest look on his face. I ask him what was the matter. He said he thought the milk was bad. It turns out, he had never heard of buttermilk and just got milk out and put in his coffee. He was being polite and drinking it!!!For the biscuits, I don't use buttermilk very often so I keep buttermilk powder in the fridge, do you think that would work for the biscuits if I reconstituted it with milk?