A Kiwi doctor says the case of a woman dying after drinking two litres of water in 20 minutes is very strange and not common at all.
It comes after Ashley Summers, a 35-year-old daycare worker from the US state of Indiana, developed hyponatremia - also known as water toxicity or water intoxication, which develops as a result of there being too much water in the body and not enough sodium. It came after she consumed roughly 64 ounces (about 1.9 litres) in about 20 minutes, causing her brain to suffer severe swelling.
Summers was on vacation at Lake Freeman, a reservoir outside of Monticello, Indiana, early last month when she began complaining of feeling lightheaded and extremely thirsty.
Her brother, Devon Miller, told ABC's WRTV Indianapolis she drank four bottles of water in about 20 minutes, which is about two litres.
After returning home, she passed out in the garage and was rushed to hospital but never regained consciousness.
General practitioner Dr Tom Mulholland described it as a "tragic case" telling AM on Tuesday he's only ever seen one case like this in his career spanning over 30 years working in emergency departments.
But he said in that case mental health played a role and the person drank over six litres.
"It does seem like not a huge amount of water to drink, especially if you're in a heat wave in the States at the moment," he said.
He told AM co-host Laura Tupou without knowing the ins and outs, it's very hard to know exactly how this was caused.
But he wondered if other factors played a role in Summers's death.
"It does happen because your sodium levels drop, your concentration drops and your brain swells and you go into a coma and you die," he explained.
"But I wonder if there's something else going on. I know they said she felt light-headed and dizziness can be a symptom of low sodium in your blood and there are other causes of low sodium.
"Drinking too much water is a very small percentage. So maybe she already had low sodium and then she went and chugged some water and made it even lower, but I don't know without looking at her records."
Dr Mulholland said a normal healthy kidney can pee a litre an hour so drinking a litre in that period of time shouldn't be a problem.
He said if people have pre-existing low sodium levels due to other conditions, such as hormonal imbalances or they're on pills that lower their sodium, then their levels will be lowered a lot more.
Dr Mulholland said there are a range of factors that determine how much water a person should drink, including temperature, the size of a person or where they're located.
"If you are sitting in Te Anau at the moment you wouldn't be chugging through too much water but if you're in Rotorua in the pools or something, you need more water," he said.
"But fortunately, I don't think people need to be rushing out to be stocking Powerade in their cupboards. Far more people have more salt so they have to retain water, which gives them high blood pressure, which kills millions of people every year. So this is a rare case."
Dr Mulholland also said the older people get, their sodium levels tend to drop.
"We are made up of water, but it's salt and water. There is magnesium and calcium and potassium and that's how we move," he explained.
Watch the full interview with Dr Tom Mulholland in the video above.
