Preheat the oven to 475 degrees. Roast the bones for 30 minutes or until well browned, add the onions, celery and carrots and roast for 30 minutes longer. Transfer bones and vegetables to a 1012 quart tall stockpot. Discard fat from roasting pan and deglaze with 2 cups of the water. Add this to the stock pot with remaining water, bouquet garni and tomato. Bring the liquid slowly to a boil, skimming often. Simmer for 4 5 hours, skimming occasionally and replenishing the water to keep the level of water somewhat constant.
Strain and discard solids; let stock come to room temperature and chill. When chilled, discard surface fat. Bring back to a simmer and adjust for seasoning. If too weak for your taste, reduce, the season with salt.
If you want to concentrate it, keep on reducing and transferring to a smaller pot until you have the consistency you want.