Cut pumpkin in half from stem to bottom. Scoop out seeds and fibers as best as you can. In a roasting pan add the water and place the pumpkin halves cut side down in the pan. Roast in the oven for about 45 minutes - this will depend on how large your pumpkin is. There should be no resistance when pierced with a pairing knife.
Remove from the oven and let sit for 10 minutes to cool off. The skin should peel off quite easily at this point. When pumpkin is cool enough to handle, put it in a food processor and puree. Remove to a cheesecloth and wring out some, most or as much as you can, of the liquid in the puree - this is dependant on what you are using it for. You can experiment with this in your recipes. Store in the refrigerator for up to 2 weeks or you can freeze.