Why dou use so much water to boil noodles?

Answer 1

Pasta added to water before it starts to boil gets a heat start on mushiness. Pasta quickly begins to break down in tepid water as the starch dissolves. You need the intense heat of boiling water to "set" the outside of the pasta, which prevents the pasta from sticking together. That's why the fast boil is so important; the water temperature drops when you add the pasta, but if you have a fast boil, the water will still be hot enough for the pasta to cook properly. http://whatscookingamerica.net/Pasta_Rice_Main/pasta.htm

Answer 2

In the early stages of cooking, starch granules on the surface of the noodles burst and release starch. At this stage, the surface of the noodles becomes sticky. A large amount of boiling water allows this starch to be diluted and washed away quickly, which prevents sticky pasta. Additionally, a larger amount of water will return to its boiling point faster after the noodles are dropped in.