https://www.sciencedaily.com/releases/2019/10/191007081721.htm > In a recent study, Waterloo researchers found that the elderly, people with impaired kidney function and those taking a combination of certain drugs need to be extra mindful of their water intake. > "People who have high blood pressure are typically given a water pill, so they pee a lot to lower their blood volume and in so doing lower their blood pressure," said Anita Layton, professor of Applied Mathematics, Pharmacy and Biology at Waterloo. "These patients are frequently also given another drug that targets a hormonal system which will affect the kidney as well.