High Water Intake to Slow Progression of Polycystic Kidney Disease

Inclusion Criteria: * Clinical diagnosis of Autosomal Dominant Polycystic Kidney Disease by history, ultrasound, CT or MRI * Healthy subjects without a diagnosis of Polycystic Kidney Disease by history, ultrasound, CT or MRI * Ages between 18 and 65 * Healthy subjects (without Polycystic Kidney Disease) must have an estimated glomerular filtration rate (eGFR by the MDRD equation) \> 60 ml/min/1.73 m2 with no history of kidney disease Exclusion Criteria: * Women who are pregnant or nursing * Active dependency on drugs or alcohol * Diagnosis of syndrome of inappropriate antidiuresis * Currently taking a vasopressin agonist or antagonist * Blood sodium level less than \< 135 mEq/L * For healthy participants, estimated glomerular filtration rate (level of kidney function) less than \< 60 ml/min/1.73 m2