Soak peas in the 6 cups of water overnight.
Transfer soaked peas and soaking liquid to a large pot and add
onions, celery, and ham hocks. Cover and cook over medium heat
until peas are tender but still whole, about 45 minutes. Add rice
and pepper, cover, and simmer for about 1 hour, or until rice
is tender.
Remove meat from ham hocks and discard bones and fat. Mix meat
into peas and rice. Serve hot.