From an ecological and water conservation perspective, boiling a large pot of water and then dumping most of the water down the drain is pretty wasteful. Since most Americans eat close to 25 pounds of pasta each year, reducing the water or shortening the cooking time could be a huge conservation step.
Harold McGee, who writes about the chemistry of cooking, decided to experiment with the amount of cooking water actually needed to cook pasta. The traditional method recommends 4 to 6 quarts of well-salted water per pound. Proponents of this method say this amount of water allows the water to quickly regain a boil after the pasta is added and provides adequate room so that the pasta does not stick together.
McGee found you could start pasta in both cold or boiling water and you could use less water, as little as 1 ½ to 2 quarts. When he started with cold water he found it took about 8 minutes to bring the pasta and water to a boil and another 10 minutes to cook. Since dry pasta absorbs very little water at cold temperatures, the cold-water method did not affect the cooked pasta.
Some well-known Italian cooks like Lidia Bastianich disagree with the cold-water method but did agree that you could reduce the cooking water. When adding pasta to boiling water it is important to stir occasionally so that the pasta does not stick.
With either the cold or boiling water method, another benefit of the reduced water is the leftover pasta water is thicker and starchier with a pleasant taste. Many Italian cooks add some pasta cooking water to sauces because it behaves like a sauce thickener, binding the flavor elements, and flavoring the pasta with its own flavor.
