That layer of white stuff is scale. You can still drink the water, but it is best not to drink this water for a long time.

1. The main components of scale are calcium carbonate and magnesium carbonate. Boilers that boil water must regularly remove scale, because scale affects heat transfer. Excessive scale may also cause the boiler to explode due to uneven local heating. Scale in the water bottle bladder also affects the thermal insulation performance of the water bottle. Since acetic acid is more acidic than carbonic acid, vinegar can be used to remove scale in homes.

2. Most natural water will produce such substances after heating. Strictly speaking, scale alone is harmful to the human body, but it is definitely acceptable to the human body and will not cause any specific harm. However, scale that has formed over a long period of time contains many sediments, along with trace metal elements produced in water boiling containers, including heavy metals such as lead, zinc, arsenic, etc., which are harmful to the human body, but not as advertised by some water purifiers. That's so alarmist! It is harmful to use a kettle without cleaning it for a long time. If you clean the kettle frequently, there will be no big problem. Just use vinegar!