Many of us take a “just in case” drink of water before leaving the house, before a meeting, or just because the bottle is there. A kidney specialist explains that this habit of “proactive hydration,” while seemingly harmless, can be a problem, contributing to a chronic state of mild overhydration.
Our bodies are not like car gas tanks that need to be topped off at every opportunity. They have a dynamic and responsive system for managing fluids. The thirst mechanism is designed to signal a need for water with plenty of time to respond before dehydration becomes an issue for the average person.
When you constantly drink “just in case,” you are overriding this system. You are adding fluid when your body’s electrolyte concentration is likely already balanced. This forces your kidneys to perform unnecessary work to excrete the surplus and re-establish that balance.
While a single “just in case” drink is unlikely to cause harm, making it a constant habit can lead to consuming far more water than you need over the course of a day. This puts you at a higher risk of diluting your electrolytes and developing symptoms associated with overhydration.
A better approach is “responsive hydration.” Wait for your body to give you the signal—thirst—and then respond. This trusts your body’s own regulatory systems and ensures you’re giving it water when it actually needs it, not just “in case.”