Are you asking about DRAINING or RINSING? Draining you do because you need to get rid of that water before mixing the pasta with sauce. Rinsing should only be done if a) the pasta is a bit overcooked. Then you rinse with cold water to stop the cooking process BEFORE adding to the sauce. If this is the case only toss it with the sauce for about 2 minutes after draining and rinsing. b) you are going to use the pasta as a cold side dish like a pasta salad or some such thing.
yeah, i don't know anyone who would want to dump 6 quarts of pasta water in their tomato sauce. i think the "point" of the question, is in the question itself.
the reason for salting the water is simple: more coverage because the salt dissolves in the water. if you salt the pasta when it's done, the salt doesn't always break down, and the flavor is inconsistent - some bites will be saltier than others. as a rule, to make good pasta, you have to generously salt it. so many people get their sauce to the perfect flavor, then toss it with the pasta and it's bland because they didn't season their pasta enough
As far as I know, it's completely safe to drink the pasta water, I certainly cook pasta in soup quite often, e.g. minestrone. The only thing is, pasta is usually coated in excess starch, so it makes your soup cloudy, if it's a clear broth you may want to cook your pasta first. The pastas I buy don't contain any preservatives, drying preserves it without adding anything artificial. Hope this helps
Mmmm...... you have to boil it to cook it so naturally some things are going to cook out, as well as the starch, - but when you rinse it you are washing off the starch that makes sauces stick. I never rinse my pasta unless I'm making macaroni salad or something that isn't swarming in sauce like that - otherwise I have to use sooooo much more dressing as it keeps attaching to the starchy exterior of the pasta.
There are some pasta sauces that you use the pasta water to thin them a bit if they get too thick. But as far as soup, if you used ALL the pasta water for your soup you would taste so much starch it wouldn't taste good. I will only cook pasta in my soups if it doesn't call for much pasta - otherwise I cook separately then add.
Did any of these explanations help with your decision to use or not use the pasta water?