The Connection Between Water and Blood Pressure

Staying properly hydrated is critical, as is keeping your blood pressure under control. But can one affect the other? Water has a host of health benefits, and the connection between water and blood pressure is one that can't be ignored.

Read more: How Can I Tell When My Body Is Hydrated?

To stay adequately hydrated, Harvard Health Publishing says that most people should drink 4 to 6 cups of water a day.

The Mayo Clinic highlights U.S. National Academies of Sciences, Engineering and Medicine research suggesting that men consume roughly 15.5 cups of fluid a day, and women consume 11.5 cups daily.

Water is sugar-free, caffeine-free, calorie-free and preservative-free, and it provides numerous health benefits to the body.

Harvard Health points out that water helps move nutrients and oxygen throughout the body, while flushing not-so-great bacteria out of the body through the bladder. It helps with digestion and prevents constipation, cushions joints and offers organ and tissue protection. It also helps regulate body temperature, while ensuring that you maintain sufficient levels of sodium and key minerals (also known as electrolytes).

In addition, water can have a heart-healthy impact, helping to stabilize heart rhythms and normalize blood pressure.

Not drinking enough water and becoming dehydrated can trigger weakness, dizziness, confusion and a drop in blood pressure, Harvard Health Publishing says.

"Water intake impacts blood pressure in that profound water depletion or dehydration can lead to low blood pressure (hypotension)," says Willie E. Lawrence, Jr., MD, chief of cardiology for Midwest Heart & Vascular Specialists in Kansas City, Missouri.

Having said that, Harvard Health cautions that optimal water intake is not the same for everyone, nor for every situation. For example, hot weather and very strenuous activity can increase daily water needs, and the Harvard Health experts advise that healthy people experiencing heavy sweating consider drinking 2 to 3 cups of water an hour until conditions normalize.

But what about too much water? Can overdrinking negatively impact blood pressure? Healthy individuals need not be too concerned.

"Water consumption within normal ranges does not impact the blood pressure," says Michael J. Blaha, MD, MPH, director of clinical research at Johns Hopkins Ciccarone Center for the Prevention of Heart Disease, in Baltimore. If you're an otherwise healthy person, "the body is generally very good at regulating overall water levels," Dr. Blaha says.

Dr. Lawrence agrees, noting that "excess water intake in the setting of normal kidney function does not play a significant role in causing high blood pressure."

Still, Dr. Blaha suggests that "patients should only drink as much as indicated by the thirst mechanism of the body." He also stresses that "patients who have heart failure or kidney issues do need to be much more careful with their water intake."

That caveat is echoed by Harvard Health Publishing. Harvard Health experts note that excessive hydration can prove problematic for those who are not in optimal health. For example, people taking non-steroidal anti-inflammatory drugs (NSAIDs), antidepressants or prescription pain medications (opioids) should be careful not to overhydrate, as such medications tend to trigger excessive water retention. Mayo Clinic experts say that can lead to a problematic condition known as hyponatremia.

Hyponatremia can develop when sodium/electrolyte concentration levels become dangerously diluted, plummeting as water levels rise. The Mayo Clinic explains that sodium (salt) levels are critical to ensuring nerve and muscle health and good blood pressure, with a normal blood sodium level hovering between 135 and 145 milliequivalents per liter (mEg/l).

However, excessive water intake can sometimes cause blood sodium to dip below 135 mEg/l. That, in turn, can cause cellular swelling, says the Mayo Clinic, which can then send blood pressure levels out of whack.

According to Harvard Health Publishing, overhydration is also risky for those struggling with certain chronic illnesses, including thyroid, kidney and liver disease. People with heart disease also need to be careful, as excessive water intake can mess with blood pressure levels.

Water is essential to both heart health and overall health. In fact, according to the Mayo Clinic, water makes up a whopping 60 percent of your body weight. Just don't drink too much or too little, and you'll be fine.

Read more: 8 Hydration Mistakes You're Probably Making and How to Fix Them