Here's an interesting article that says what used to be the three-legged stool of retirement (Social Security, pensions and personal savings) is now a four-legged stool of retirement (Social Security, employer retirement plans, home equity and work.) We'll start with their thoughts on Social Security:
One liter of water weighs 1 kg., and 1 gallon of water is equal to 3.7854118 liters; therefor, 1 gallon weighs 3.7854118 kg, which is 8.345404487293294 pounds. Fresh water is take 39.2 degrees Fahrenheit . 1 gallon of fresh water is about 8.36 pounds (Gallon of water weigh calculator). For US: 128 ounces to a gallon, about 30 g/ounce (memory says 29.6g/oz but I would not trust my life on it.) 128*29.6g = 3788.8g = 3.788.8 Kg *2.2lb/kg about = 8.33lb.
Water weighs quite a bit too. That makes it a pain to keep enough with you in the wilderness. Weight of Water Pounds Kilograms Cubic cm. 0.0022 0.0010 Liter 2.2047 1.0000 Cubic inch 0.0361 0.0164 Gallon 8.3454 3.7854 Cubic foot62.428028.3169. You can see that the weight of a gallon of water is over 8 pounds. Now, that can make a pack awful heavy awful fast! The molecular weight of water is the combined weight of its two hydrogen atoms and one oxygen atom which amounts to 18.015 atomic mass units. The unit weight of water or specific weight of water is the same as the weight of one gallon of water.