Wash and rinse the 10 grain rice for several times until the water turns clear. Soak the rice with water for at least one hour.
Rinse and soak dried scallops with hot water for 10 minutes. Then break the scallops into small pieces. Reserve the soaking water.
Remove any excess skin and fat from the chicken. Rinse with cold water. Blanch in boiling water, drain and rinse again with cold water. Set aside.
In a large stock pot, spread the chopped pumpkins at the bottom of the pot and place the chicken on top. Put the sliced gingers and dried scallops inside the chicken. Sprinkle the soaked rice over all the ingredients. Lastly, add the water. This will help to prevent the rice from sticking to the bottom.
Bring it to a boil under medium heat, reduce heat to low and simmer for 2 hours or until the congee reaches the consistency you desire. After 1 hour, the rice should have broken and developed starch. To avoid the congee from sticking to the bottom, give it a stir occasionally. Add a little bit water if the congee is too thick. Skim off any fat or scums that float to the surface.