The groundwater in large areas of India and Sri Lanka are contaminated with high levels of fluoride.

https://www.researchgate.net/publication/248923815_The_fluoride_problem_in_the_ground_water_of_Sri_Lanka_-_environmental_management_and_health

http://schools.indiawaterportal.org/wq-test/fluoride-factsheet

Unfortunately, almost all the tea growing regions in both countries are affected, and this is why these teas have such high levels of fluorine.

I think that tea from India like Darjeeling, and Orange Pekoe from Sri Lanka tastes fantastic (not the stuff you get in America, if you're ever in India or Sri Lanka and get a chance to have local tea, you'll know) But you're going to get a large dose of fluoride when you drink it.

Bangladesh and Pakistan are affected by this also. A little known fact is that the famous pink salt from Pakistan contains lots of fluoride.

If you are going to be living for more than a few months in India or anywhere else in South Asia, you should be aware that the tap water in affected areas can contain massive amounts of fluoride, more than in cities that fluoridate their tap water.

Also, while it's true that natural sources of fluoride like calcium fluoride are not as bad for you as as the fluorosilicic acid cities in America use, there's way too much calcium fluoride in many parts of South Asia. Kids get weak, mottled teeth. Farm animals get mangy fur. The government of India is devoting a lot of research to the development of large-scale defluoridation technologies.

Sources?

No way does an 80 year old woman drink 4 liters of anything in a day. It might have been 4 cups.

This is the correct answer, but in addition to that it's worth mentioning that drinking water is fluoridated with fluorosilicic acid , which is a highly aggressive form of fluoride.

This is, they say, to prevent cavities. But it's a completely ridiculous notion to assume all the fluoride from your drinking water is going to end up on your teeth. It can go anywhere in your body , including organs in the brain like the pituitary gland (which has a high concentration of calcium, very attractive for fluoride). You don't want your pituitary gland full of fluoride. Or what about your bones? Do you want fluoride in your bones, or skeletal fluorosis?

Putting industrial waste called fluorosilicic acid into drinking water is like trying to drink plaster in order to prevent wounds and cuts.

In addition to the difference between natural fluoride (calcium fluoride) vs drinking water fluoride (fluorosilicic acid) this documentary will explain what the problem is:

https://www.youtube.com/watch?v=GqstwfKGzPI

4 liters? Damn thats a lot of tea.

They leave it in to avoid processing it out of groundwater. Its terrible for your bones, and can cause joint pain in excessive amounts.

DOUBLE FLUORIDE POWER

And how's that working out for them?