Did you know sucking fresh lemons or limes can have a detrimental impact on tooth enamel? The acidic pH of these citrus fruits can create an acidic oral environment, which allows for minerals to leech out of tooth enamel. A bit of lemon juice diluted in drinking water is not likely going to have the same negative impact. Diluted is the key.
In fact, a study in Brazil showed essential oils of lemon to be beneficial in inhibiting oral microorganisms.
If you like lemon water, drink up. If you are concerned about possible effects of demineralization – talk to your dental hygienist.
Reference: http://www.scielo.br/scielo.php pid=S180683242014000100217&script=sci_arttext&tlng=pt