There are different kinds of plastics.We generally use PET bottles for drinking water.
The bottles which tend to be highly flexible are good enough to use only once. They are not good for continuous use.
If you keep water in it & place it exposed to sunlight, the plastic in the bottle will slowly melt & mix with the water inside.
This has the potential to cause a lot of physical harms to the body.
It is important to keep these bottles in the right temperature range.PET bottles should not be used for years together.
If you detect the smell of plastic in the water, please change the bottle immediately.
It is normal for children to sip water directly from the bottle keeping their mouths on it. So, there is a chance that bacteria may enter the children`s bodies.
If the mouth of the bottle is narrow, it is not possible to clean the bottle with brush regularly.
It is not advisable to wash it with soap either.So, it is better to throw the bottle away after 4 months use.
Only when a triangle along with a number is indicated in the bottom of the bottle, it is of a good quality plastic. If the umber mentioned in the bottom of the bottle is 2 or 5, they are ok to buy.
If you buy water bottles made from recycled plastic, avoid choosing dark colours.