Most children of school age who wet the bed at night have what doctors term primary enuresis.. They have never had nighttime control of their bladder. Family history plays a role, too, in incontinence in children. If you wet the bed as a child, don't be surprised when your child does, too.
One thing to notice is that if you put a gallon of air on a scale, (in a wieghtless container, of course) you would measure zero, exactly. That's because the buoyancy caused by the surrounding air exactly counteracts the weight of the air in the container. If you pressurized the air in your gallon container to, say ten times the outside pressure (or 147.0 psi absolute, or 132.3 psi gauge) it would now weigh nine times 0.01, or 0.09 lb.
One cubic foot of water contains 7.48 gallons of water, weighing in at 62.31 pounds. The Handbook of Chemistry and Physics specifies the weight of 1 US gallon of water in air at 68 degrees F to be 8.32487 pounds or 3776.103 grams. To say the temperature of the water affects the weight is somewhat misleading.