There is no harm in drinking water left overnight if it is stored properly.. Always cover the water kept in a glass or open container. Never put your mouth to the bottle and if you have, finish the entire bottle in one go. Do not leave the water bottle in your car.
If left in the open, your water may taste slightly different since it will absorb carbon dioxide. For this reason, the recommended period is to consume the water 3 days following the day it was opened.
If needed, open water bottles should be stored in the fridge to slow bacterial growth. According to the shelf-life gurus at Still Tasty, a continuously refrigerated bottle of water can maintain quality for four to six days after opening.
Bacteria, fungi and even mold can thrive in a water bottle, thanks mainly to its moist environment. Simply rinsing the bottle out with water isn't sufficient, and care must be taken when cleaning bottles that have attached straws and narrow-mouth lids with lots of nooks and crannies.
An unopened bottle presents minimal risk, especially if the alternative is dehydration. You should avoid drinking from a water bottle that's been opened and then left in a hot space. Hot vehicles provide the perfect breeding ground for bacteria to grow, so it's best to toss any opened bottles left in your car.
The water left overnight or for a long period of time in an open glass or container is home to numerous bacterias and is not safe for drinking. You never know how much dust, debris, and other small microscopic particles might have passed into that glass. Water left in a bottle for a long time is not safe to drink.
Overall, both tap and bottled water are considered good ways to hydrate. However, tap water is generally a better option, as it's just as safe as bottled water but costs considerably less and has a much lower environmental impact. Plus, with a reusable water bottle, tap water can be just as convenient as bottled.
By drinking an opened water bottle over a period of time humans become susceptible to food poisoning with symptoms of vomiting and diarrhea. These bacteria are known to cause heart disease, whooping cough, and bronchitis.
After around 12 hours, our tap water can go flat as the carbon dioxide in the air mixes with the water. This lowers the pH level of the drinking water, and this process imparts a stale, lifeless taste. Although the drinking water is still safe to drink, it's less palatable, and many people won't enjoy the taste at all.
“The hotter it gets, the more the stuff in plastic can move into food or drinking water.” Drinking from a single water bottle left in the hot sun won't hurt you, but experts say consumers should avoid persistant exposure to plastic containers left in extreme heat.
“Most experts will tell you tap water has a shelf-life of six months,” Satterfield says.
When you leave the glass of water uncovered for about 12 hours, carbon dioxide in the air starts to mix with it. This reduces the pH level of the water and gives it an off taste. But even then this water is safe to drink.
Contaminated bottled water can harm your health, including causing gastrointestinal illness, reproductive problems, and neurological disorders.
By drinking an opened water bottle over a period of time humans become susceptible to food poisoning with symptoms of vomiting and diarrhea. These bacteria are known to cause heart disease, whooping cough, and bronchitis.
WATER, COMMERCIALLY BOTTLED - OPENED
The precise answer depends to a large extent on storage conditions — keep opened bottled water refrigerated and tightly closed.
One of the main reasons to avoid drinking chilled water is because it has a serious implication on your digestion. Chilled water as well as some cold beverages contract the blood vessels and also restrict digestion. The natural process of absorbing nutrients during digestion is hindered when you consume chilled water.
The study found that bottled water is safe in 70 degree Fahrenheit weather, but during hotter days, that's not the case.
After around 12 hours, our tap water can go flat as the carbon dioxide in the air mixes with the water. This lowers the pH level of the drinking water, and this process imparts a stale, lifeless taste. Although the drinking water is still safe to drink, it's less palatable, and many people won't enjoy the taste at all.
“If it's allowed to incubate for hours, that could potentially contaminate the water, and make you ill by reintroducing that bacteria,” says Marc Leavey, MD, primary care specialist at Mercy Medical Center in Massachusetts.
The bottom line. Tap water can be stored safely for up to 6 months. Certain chemicals found in plastic can leach into bottled water over time, which could potentially damage your health. Thus, it's probably best to avoid commercially bottled water that's far past its expiration date.
Bottled and tap water were tested using standard microbiology culture techniques. The bacterial count in bottled water increased dramatically, from less than 1 colony per milliliter (col/mL) to 38,000 col/mL over 48 hours of storage at 37 degrees C.
However, there are chemicals in the plastic that may end up in the bottled water. It is also possible to find bacteria in bottled water!
All in all, water in plastic bottles should be safe to drink, and no less so than water in metal bottles or any other type of container. If they have contaminants in them, they are likely to be found at tiny concentrations.
Even without one, much of the chlorine present in tap water from the filtration plants evaporates when water is left to sit uncovered. Even if you are only refrigerating tap water, the results will be purer and more refreshing even than most bottled water.