Ashley Summers was on vacation with her family when she died from a rare complication caused by her sodium levels dropping rapidly

A Monticello, Indiana, mom of two has died after drinking too much water too quickly in a rare, but fatal case of “water toxicity.”

Ashley Summers, 35, was on vacation with her family on Lake Freeman over Fourth of July weekend when she landed in the hospital, according to a report on WRTV.

“They were out on the boat all weekend long,” her older brother, Devon Miller, told the news station. “She loved being on the water. She loved being on the lake.”

On Tuesday, July 4, Summers had reportedly felt dehydrated, saying she had a headache and felt lightheaded.

That’s when she began drinking a lot of water — in a short period of time.

“Someone said she drank four bottles of water in that 20 minutes. I mean, an average water bottle is like 16 ounces, so that was 64 ounces that she drank in the span of 20 minutes. That’s half a gallon,” said Miller.

According to the Mayo Clinic, women should consume about 2.7 liters of fluids a day — about 91 ounces — with 20% of that coming from food.

When Summers got home, she passed out in her garage — and never regained consciousness.

“My sister, Holly, called me, and she was just an absolute wreck. She was like ‘Ashley is in the hospital. She has brain swelling, they don’t know what’s causing it, they don’t know what they can do to get it to go down, and it’s not looking good,’” said Miller.

The cause: Hyponatremia — also known as water toxicity, which occurs when the amount of sodium in your blood is “abnormally low” according to the Mayo Clinic.

“Drinking too much water [can] cause the sodium in your body to become diluted. When this happens, your body’s water levels rise, and your cells begin to swell,” the Mayo Clinic adds.

And for Summers, drinking too much water proved fatal.

“It was a shock to all of us when they first started talking about water toxicity. And it was like, ‘This is a thing?’” Miller told WRTV.

While rare, water toxicity can be fatal. The Cleveland Clinic cautions that some underlying medical conditions, and consuming alcohol — particularly beer — can increase your risk of it.

Also called “water intoxication,” the Nation Institute of Health noted that “early detection is crucial to prevent severe hyponatremia, which can lead to seizures, coma, and death.”

The Harvard School of Public Health noted that while athletes and those with kidney problems are more prone to hyponatremia, “women and children are also more susceptible to hyponatremia because of their smaller body size.”