Add the water, onion, garlic, celery, carrot, potato, and tomatoes to a large pot.
Bring to a boil, then reduce to a gentle simmer.
Cover and cook for 5 minutes.
Stir in the lentils, cover, and continue cooking for about 30 minutes, or until the lentils and vegetables are tender. Stir occasionally.
Add the basil and parsley during the last 5 minutes of cooking.
For a thicker soup: Mash some of the potatoes and lentils against the side of the pot, then stir them back into the soup.
