Answer: 1 liter
Patient with heart failure has a weak heart contraction that makes the blood filtered by the kidney decreased. Decreased urine and weak heart contraction can lead fluid retention. The amount of fluid can be counted by weighing the patient. Since water density is 1kg/l the patient weight increased by 2lb, then the amount of water would be: 2lb* (1kg/2lb) / (1kg/l)= 1 liter of water.