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.
1 So a gallon of salt water weighs 8.556 lbs.  That's a common expression. A pint is 16 fluid ounces and 16 fluid ounces of water weighs approximately 16 dry ounces. Two pints to the quart, four quarts to the gallon means eight pints to the gallon, so a gallon weighs about eight pounds. But that only applies to FRESH water. Salt water has a whole range, depending on how much salt is dissolved in the water. So you'd have to add the weight of the dissolved salt.