Lemon water or apple cider vinegar daily is not bad for your teeth.
Fact is, this is NOT TRUE.
While lemon water and apple cider vinegar may help with gut health, they may have detrimental effects on teeth which are irreversible. The truth is that frequent exposures to acidic foods can erode enamel, making teeth more susceptible to decay over time.
It's also a myth that brushing straight after gets rid of the damage, as it actually makes things worse. Brushing immediately after eating or drinking high-acid foods, may strip enamel that has been softened by acid. So even though a squeeze of lemon or lime can turn a simple glass of water into a fun beverage, it's not always the best choice for your mouth. Make sure to drink plenty of plain water.
BOTTOM LINE: The acid in lemon or apple cider vinegar may weaken dental enamel and lead to loss of minerals that may cause tooth decay. Wait at least half an hour after consuming high acidic foods or drinks, and then start brushing. In the meantime, you can always rinse your mouth with tap water.