With record-breaking temperatures being reported all over the United States, medical experts have been reminding people about the importance of staying hydrated.

But can a person drink too much water? Yes, according to the Centers for Disease Control and Prevention.

The agency advises people to drink no more than 48 ounces – or six cups – per hour. Consuming more than that will lower the concentration of salt in one’s blood, which can trigger a dangerous chain of events, says Dr. Mahesh Polavarapu, the medical director at New York-Presbyterian Westchester. “If you have too much water, it’s going to basically push that water into cells to kind of balance out that sodium and other electrolyte concentrations,” Polavarapu says. “So as that happens, your brain cells and other cells in your body start to swell.”

What’s more is detecting overhydration can be tricky because many of its symptoms – like nausea, cramps, and fatigue – mimic those associated with dehydration, according to the Mayo Clinic’s Jason Ewoldt. “Being aware of thirst and urine color is the easiest way to limit the possibility of both overhydration and dehydration,” Ewoldt says, noting that clear urine could be a sign that a person is drinking too much water.