Reminds me of the the whole bomb-shelter idea-I don't care how much food and water you have,flashlights,batteries etc. Eventually You,your wife,2.5 children,dog and cat will need to go to the bathroom and a small bunker will eventually be ripe with smells,disease and bad tempers.Watch out when the dog starts eyeing the youngest as a food source too.
On the other side-if you have a yard and can get outside I saw in Cabela's -and probably sold elsewhere this container you place in the ground and add some enzyme to the waste and it decomposes it naturally-called a doggie dooley waste disposal system.I would imagine that it would be effective for human waste issues as well and more discreet than having a portable bathroom in the yard or using bags and no real means of getting rid of the waste.