Polycystic kidney disease (PKD) is a genetic disease that occurs in 1 in 500 individuals and leads to kidney failure in half of all affected. Currently, no treatments exist for PKD. PKD-affected kidney cells divide and multiply inappropriately, and form fluid-filled sacs called cysts. Kidney cysts continue to grow throughout life, destroying normal kidney tissue, leading to kidney failure. Based on evidence from basic science research it is believed that drinking high amounts of water can slow the abnormal cysts growth. This study aims to look at changes in urine composition with high water intake in PKD-affected persons compared to healthy individuals.