Medical Reports: H2-Oh-No

WSVN -- Water -- it's everywhere.

We pack it, stack it, run it, guzzle it, and, when it comes to H20, many of us believe the purer the better.

Irene Sintow: "I don't remember the last time I drank tap water."

From the fridge to the sink, Irene Sintow's water is filtered out with a home system.

Irene Sintow: "I was concerned about impurities in the city water, and I didn't want to be drinking it -- I didn't want my family drinking it."

But while many of us think purified water is healthier for us, new studies show we might be hurting our hearts by taking out an important mineral -- magnesium.

Dr. Paul Hunter: "The evidence is that Americans often do not have enough magnesium in their diet generally, and removing it from the water actually adds to that deficit."

Dr. Paul Hunter is head of the World Health Organization.

According to a startling report it recently released, there is a link between filtered water and increased death from heart disease.

The problem is, during the purification process, water treatment centers, home filtration systems and bottled water companies often end up removing magnesium -- a mineral that's vital for heart function.

Dr. Ethan Sieve: "There isn't a cardiologist in town that hasn't seen abnormal heart rhythms associated with magnesium. We're talking about life-threatening arrhythmias and people can actually have cardiac arrests if these things remain untreated."

The World Health Organization recommends a minimum of 10 milligrams of magnesium per liter.

But none of the water we had tested met that requirement.

Water from Irene's home filtration system had only three milligrams per liter.

A popular bottled water -- four milligrams.

When it came to tap water, Broward water contained the most, with six milligrams -- Dade, only three milligrams.

Rafael Terrero: "During the treatment process, a lot of minerals are taken out of the water quality, one of them is magnesium, which is reduced."

Unfortunately in Miami-Dade, changing the purification process comes down to cash.

Rafael Terrero: "I don't think we would be doing this at this time. It would take a lot of studies and would be very expensive."

To get more magnesium in your diet, you can start by adding a daily supplement to your water.

Also try eating nuts, spinach and broccoli.

And if you are buying bottled water, make sure minerals are included.

Dr. Ethan Sieve: "Take a look at the label because, sometimes, it's mineral water where they add the minerals in, and sometimes it's purely de-mineralized water."

Irene and her family are still filtered in, but now they're looking for ways to stay hydrated and heart healthy.

Irene Sintow: "I do myself. I take magnesium, and I take calcium."

Doctors also suggest baking or microwaving your veggies.

Boiling with de-mineralized water can often leach minerals out of your greens, taking away the nutritional value.