1. In a pan, heat the olive oil and saute the onions till translucent.
2. Add the garlic and saute for 1 1/2 minutes.
3. Add the basil leaves, dry oregano, pepper and salt and stir.
4. Add the water and simmer for 4-5 minutes.
5. Add the crushed tomatoes and tomato sauce and stir and bring to boil.
6. Once it start sto boil, simmer for 30-45 minutes.
7. Serve with spaghetti.
You can freeze the marinara sauce and use later for other dishes.