It depends on how long you are camping, and how many bodies you are taking with you. I say bodies as I have two dogs and they typically go through about 1.5 gallons per day. For people and cookinig/clean up, we figure on 3-4 gallons per day. So, without showering, I typically take 5 gallons per 24 hour period for 2 people and 2 dogs. I have gone 3 days with 10 gallons, but we conserved a bit, so that is just rough guidelines that I follow. Since most of our trips are 2-4 days, I am set up with 15 gallons which is about 100lbs.