Most people will agree that they refill their used glass of water rather than washing it in between uses. After all, it's only water, right? What happens if we don't wash that glass of plain water and keep drinking from it for a week?

The answer is negative, and it should make you want to thoroughly clean that glass or refillable water bottle before getting a refill. This seemingly innocuous habit may endanger your health.

You are unknowingly exposing yourself to health risks. Water is necessary for all bodily functions. Drinking from a dirty glass, on the other hand, may expose you to harmful bacteria and increase your risk of illness.

A dirty glass is no longer simply one that is dusty.

A used glass of water that does not appear to be "dirty" could also cause a nasty illness. Doctors note that norovirus can survive in an unwashed glass for a week or more if not properly cleaned. Vomiting and diarrhoea are symptoms of this highly contagious virus.

Bacteria will grow even if you simply refill the container.

If you use the same glass of water without washing it for a week, bacteria will begin to grow on its surface. Even if you refill it with fresh water, bacteria can quickly multiply and become dangerous to your health on that unwashed glass.

Use soap and water to clean

Some people simply wash the glass with water. To remove the harmful bacteria, however, you should scrub the glass with both soap and water. Without washing and scrubbing these glasses, the bacteria will continue to replicate and multiply. Bacteria can form a colony known as a "biofilm" over time.

Leaving water out can be problematic

Another common practise before going to bed or working is sleeping/sitting with a glass of water left out in the open air. It is important to remember that the water you will eventually drink may have been exposed to airborne bacteria from dust particles or other sources around the glass. Before going to bed, keep a water bottle with a lid on your nightstand.

Continue to change the water!

Aside from cleaning your water bottle or glass of water, it is also critical to refill your container with fresh water on a daily basis. Bacteria can grow in water that hasn't been changed in a few days.

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