In a strainer, rinse the split peas very well, until the water runs clear.
Add the split peas to a large, heavy bottomed pot. Stir in the water. Bring to a boil, cover, turn down the heat to medium-low, and simmer for 1 hour.
Uncover and stir in the carrots, celery, onion, leeks, potatoes, parsley, and vegetable bullion cubes. Cook for about 20 minutes, until the vegetables are tender.
Stir in the sausage.
Cook and refrigerate over night. Reheat and check for seasoning, adding salt and pepper if necessary. Serve with warm buttered bread.
Notes
This soup also freezes extremely well! Simply defrost and heat through when you are ready to eat it!