07-18-2010, 05:43 AM
I would think location is the key to this question. The higher the elevation the more rain you are going to get and the smaller the tank you'll need. With 7 people in the family I'd be in a wetter part of the island or find property in a subdivision that has a water system. Age and gender of the kids can play a big roll in water usage.
Royall
Royall