Sometimes, you might not finish drinking your glass of water before you go to bed. You might want to drink it the next morning. But have you ever wondered if it is still safe to drink?
"If you have clean water in a clean glass, you're fine to drink it for a day or two," Kellogg Schwab from the Johns Hopkins University Water Institute in the US told Time.
But you may find that it tastes strange. That's because after about 12 hours, the carbon dioxide in the air reacts with the water in your glass, slightly lowering its pH level.
Also, there might be more microorganisms in your water if you leave it out overnight. Microorganisms grow more quickly at room temperature. These microorganisms can stick to your glass. They can make you get sick more easily. But as long as you clean your glasses very often, this will not be a problem.
In countries like the US and UK, people often drink water directly from the tap. This is OK—however, tap water cannot be stored for a long time. Most experts say that tap water has a shelf life of six months, according to Zane Satterfield from West Virginia University, US. After six months, there is less chlorine in the water and bacteria start to grow. You'd better not drink the water otherwise you may get sick.
What about plastic water bottles? Schwab said people should be careful with them. If you leave a bottle of water under the sun or in a car for a long period of time, the plastic produces a chemical called BPA. This chemical can cause heart disease and cancer.
