Mom of 2 dies of water intoxication, family says

A family in Indiana is mourning the loss of a 35-year-old mother-of-two who they said died after drinking 64 ounces of water in 20 minutes.

Ashley Summers was celebrating the Fourth of July on a lake in Indiana when she started to feel intensely dehydrated, according to her brother, Devon Miller.

"At one point during the day, she started getting a bad headache," Miller told "Good Morning America." "So, she was drinking a lot of water."

Miller said Summers drank the equivalent of four 16-ounce bottles of water in 20 minutes, and then later collapsed inside the garage of her home.

"She felt dizzy and had this headache," Miller said. "They got home. She walked across the garage to go into the house and she passed out in the garage."

Miller said doctors told the family that Summers died of water intoxication, a rare but dangerous condition caused by drinking too much water too fast, which upsets the electrolyte balance in the body, according to research published by the National Institutes of Health.

Symptoms of overhydration may include "altered mental status, disorientation, confusion, nausea, and vomiting," according to the research.

If water intoxication is not detected early, it can lead to seizures or coma.

Dr. Stephanie Widmer, an ABC News medical contributor, board-certified emergency medicine physician and medical toxicologist, said the key to preventing water intoxication is spacing out the intake of water throughout the day.

"The general recommendation is two liters of water per day, on average, per person, and that's throughout the day," Widmer told "GMA." "But you also don't want to consume more than one liter [of water] per hour."

Miller said he believes that was the case for his sister, who is survived by a husband and two children, in addition to other family members.

"If she would have spaced out her water consumption, she probably would be alive today," Miller said.

Summers was an organ donor, a silver lining in which Miller said his family is finding hope while mourning her death.

"They were able to get her heart, her lungs, her liver, her kidneys and her long bone tissue," he said. "Five individuals are getting a second lease on life because of her generous donation."