Why is there a watery run-off after cooking my bolognese?

A few things that can help, if it's not an issue with fat like @Aaronut suggested:

• Tomato paste. Yes, I know it's a sacrelige, but it'll act as a thickener.
• Take the pasta out before it's gotten to al dente, and finish cooking it in the sauce; the pasta will absorb any extra liquid, and help to thicken the sauce.
• Do not rinse off the pasta after you drain it. Way too many people do, and it washes off the starch that you want for the sauce to bind to the pasta properly, and may introduce extra water.

Cooking longer and slowly will help. Also, are your vegetables fully cooked when you add them to your base? That could be the problem if they are not.

That run-off you're seeing is probably not water, but fat separating. Touch or taste a bit of the liquid; if it seems oily at all, then it's fat.

When making bolognese, if you don't want this to happen, you need to frequently skim off the fat that rises to the top. If you just stir it back in, it will separate again later.

You should also cook it slowly (skimming often) for a good 4 hours or so.

I should note that the fat is not necessarily evil and some cooks insist that you should never skim, because that's where the flavour is. Personally, I've never found much difference in the flavour whether you skim or not - but if you don't skim, the fat content causes the mixture to separate later.

The same thing happens with chili, or any dish where you're using ground chuck that hasn't already had all the fat removed by deep browning. Eventually, during cooking, that fat will leave the meat, and you have to either skim it off, cook it off, or contend with greasiness.

I have had this problem of water on the plate too.

Fully drained pasta (not rinsed) and added back to the dry pot for extra drying out. Sauce made with passata, wine, fully cooked veggies - and cooked for hours.

After all this, still that small pool of water on the plate. Annoying.

My solution is to pour the sauce into a sieve / strainer and let the small amount of water run out. It is just water, not fat, and not adding any flavor.

It seems that all spagetti sauce separates, regardless of who makes it, excepting those who use starch to thicken it....ugh.

Simple, make nests of spagetti, ladle the sauce on it, tilt the plate, and lay a few paper towels at the edge of the nest of sauce laden spagetti. In a minute or two the watery stuff separates and goes into the paper towel. Remove the watery laden towel and throw it away and voila! The remaining sauces is no longer watery.

And no...all the sauces that do this--it's not fat separating it's water.

To avoid watery spaghetti on the plate, drain spaghetti, do not rinse. Dump the spaghetti into the sauce. Make sure its al dente. Wait about 10 minutes and serve. You will have no watery spaghetti on your plate.

Passata is not the base of any authentic Bolognese sauce. That is your problem. Soffritto is the base of Bolognese, and only a small amount of tomato should be added to it mid-way. Switching from tomato-based to soffritto-based sauce fixed my Bolognese, and I bet it will for you as well. Look up Marcella Hazan's recipe.

So after years and years of the same problem i finally had full success last night. The key was heat! Heat as in don't let the sauce or noodles be too hot! If your like me you cook your meat sauce for an hour or two and put it on top of your noodles. I've tried everything in this posts without much luck. While adding your noodles to your sauce does work my problem is i usually make a pretty big batch of sauce. Who wants all sauce with a few noodles, or all noodles with little sauce? After you've cooked your sauce to your satisfaction take the lid off and let it sit/ cool with an occasional stir while you cook your noodles. Drain your noodles and let them quit steaming. Put it all together and problem solved. Both the noodles and sauce are still plenty hot enough to enjoy but by doing this neither are hot enough to allow the moisture in the noodles to end up pooling water on the bottom of your plate.

I have made pasta sauce from scratch with mince for decades and never had any water run off until......i bought the most expensive lean beef mince from an artisan farm and each time i put it on the plate a hell of a lot of water seeps out like magic....its like soup. So the answer is but mince that has more fat content.