Hydrocephalus is water on the brain and the usual treatment is put put drainage tubes in the head. How old it the patient? Is the head enlarged? Surgery can be done to remove the fluid. The biggest problem is the pressure on the brain and if it's great enough seizures,convulsions can occur. In adults,headaches increasing in severity may be the 1 sign. In children, the fluid can inhibit normal development of the brain, interfere with growth and if the brain does not have the pressure relieved death is possible. As for how long someone can live, to a certain extent it depends on the cause of the problem. An accident, or a birth defect, even heat exhaustion can cause this problem. In the case of outside interference e.g. Surgery will help. A birth defect can be treated with drainage tubes and the child may out grow it. I wish you luck. I know it's not a true answer, as in a definite time period but with treatment and care, it could be a long time (natural life span).
