Death because of distilled water consumption

Question

One of my friends said that I would die if I drank distilled water (we were using it in a chemistry experiment) I gave it a go and surprisingly did not die.

I did a bit of Googling and found this

It said that drinking only this kind of water could definitely cause death, as distilled water was highly hypotonic and it would make the blood cells expand and finally explode and ultimately cause death.

I wanted to know exactly how much of this water on an average was needed to be consumed to cause death.

Answer 1

Drinking a little bit of distilled water is not generally fatal. Drinking only this kind of water will be fatal because it is highly hypotonic as you've found out. Let me simplify and explain wy this is the case.

Salt balance in the body is largely maintained by passive diffusion. Salts diffuse from areas of relatively high concentrtion (eg, stomach) down to areas of low concentration. For example, if you have just eaten a meal, the stomach contents are relatively higher in salt concentration compared to the surrounding tissue and the blood. Salt diffuses out of the stomach and into the stomach lining, intestines and blood. Tissues have to make sure they don't get too much salt or they will take in too much water and burst, so they have active transport mechanisms to remove excess salts and they go into the blood as well. Now that the excess salts are carried in the blood, they ultimately get filtered at the kidneys and excreted in urine. The kidneys are able to filter the salt by taking advantage of this gradient moving salt once again from high to low concentrations. The exact details are not important for this discussion, other than to know the kidneys need a highly concentrated store of salt to function.

Distilled water on the other hand, has no salt. It is pure water. Distilled water will pull salt out of the tissues because now it is the absolute lowest concentration of salt. Tissues will also take in a lot of this water because it too passively diffuses and it is hypotonic. When this happens in the blood, red blood cells tend to burst because they can't tolerate a terribly large change in tonicity, and so some red blood cells die. The other problem is also that the salt control mechanisms in the kidneys malfunction because too much salt gets leeched out of them and passed in your urine.

After drinking too much distilled water, electrolytes and important minerals get leeched out of your body and this creates electrical abnormalities in your body leading to irregular and weak heart beats (from hyponatremia and hypokalemia), poor muscle strength, high blood pressure and fatigue. Distilled water as mentioned, is fairly acidity (can be as low as pH 3 when freshly distilled) and leads to acidification of the blood (acidosis).

There is no exact amount of water that one needs to drink to die. This mode of death is related to hyperhydration/water intoxication. This can happen from over-hydrating with regular tap water, but will take longer than distilled water because of the salt content in tap water.

Answer 2

I'm extremely skeptical of @leonardo's answer. I suspect that what would happen if you drank only distilled water is nothing perceptible. The only place where concentrations of distilled water would ever be high enough to conceivably matter is in the tissues of the mouth and throat, and even there, the effect would be temporary.

Compare drinking 8 glasses of either distilled or tap water every day. With tap water, you're looking at less than 200 ppm of Mg, Na, K, and Ca combined. That's less than 400mg of total mineral content per day. Given that the combined RDA of all of those minerals is on the order of 7g for an adult male, this is not nothing, but it's certainly small. Your dietary intake of these minerals probably varies by more than this daily, and your intestines, kidneys, sweat glands and mineral storage organs (like your bones and muscles) are constantly maintaining the mineral blood levels within a very narrow range, despite handling a throughput of several pounds of water and food daily. They might have to work slightly harder to manage this range if you drank nothing but distilled water, but in a healthy adult, normal intakes already vary by more than this amount without major problems. For example, the average American consumes more than 3.4 grams of sodium daily, while a low-sodium diet is on the order of 2g. Low-sodium diets have been widely studied in the medical literature, and are considered safe.

As for pH, the lowered pH is caused by increased carbon-dioxide absorption to form carbonic acid. Just as carbon dioxide is more soluble in distilled water, it is less soluble in stomach acid, and may be burped out. Would you die of acidosis from drinking seltzer water all the time? If that were the case, I'm sure there would be big health warnings about drinking soda, while it seems relatively benign. Furthermore, your body produces and excretes (through the lungs) around 1kg of CO2 daily, dwarfing any extra CO2 you might get by drinking distilled water. If the small amounts of CO2 found in distilled water were dangerous, jogging would be invariably fatal.

If you were to drink nothing but distilled water, and eat no food, you probably would die of hyponatremia within a few weeks. But you would also die of hyponatremia if you were to drink nothing but tap water, though perhaps slightly more slowly.

Answer 3

I'm not sure why no one mentions this, but any food you eat would negate this effect entirely.

Assuming then, that you had no food, the lack of minerals in this pure water would simply be another deprivation for your body. The intestinal track actively reabsorbs ions, countering this. However, in this water-only deprivation, those mechanisms might fail as some are glucose dependent.

Answer 4

Just going to add some anecdotal evidence to this discussion, which I found because I was looking for hyponatremia caused by distilled water. My dad is a 71-year-old lymphoma patient who has been suffering with bouts of hyponatremia, one time serious enough to put him in the ICU until his electrolytes were balanced (his sodium was 119). His doctors were baffled at what was causing his hyponatremia, having ruled out organ failure and some drug-related causes because the other lab values they expected to be low or high were not. Finally this past week, someone thought to inquire about what he was drinking, and he let them know that he drinks only distilled water (no soda, tea, sports drinks, tap water, etc.). I have no idea why or when this started, but it's been going on for some time. I looked back through his historic labs and saw that his sodium was below normal at 133 even before his cancer was diagnosed. Since he's started chemo, he occasionally drinks a LOT of water, and this is probably what has caused the serious episodes (122, 119, etc.). Each time his values dropped low, his legs swelled up and he would put on 10 lbs. of fluid weight in a single day.

Scary stuff. Again, no idea why he was using distilled water as his drinking water. But there you have it. He is switching to mineral water. :)