Have you ever been told that tea dehydrates you? Whoever told you is wrong.
The claim that tea dehydrates is a long-standing myth. While tea does contain caffeine, it only starts to have a diuretic effect once you’ve consumed 300mg. It’s also been found that most tea drinkers are safe to consume up to 400mg a day (though pregnant women should limit their caffeine intake to 300mg). Considering the average cup of tea has less than 50mg of caffeine, even the most prolific tea drinkers should be pretty safe.
So there you have it. Tea hydrates. Just thought you ought to know.
Need more evidence? Check out this study that looked at the hydration vs. dehydration question, among other important issues.