I learned something interesting the other day while getting my teeth cleaned.  
My hygienist is very up on nutrition and actually eats right (unlike me who 
doesn't practice what I preach.)  I asked her if drinking lemon juice in water 
would be harmful to my teeth.  She said no, not if I follow a few 
guidelines......

Drink the lemon juice water in a relatively short amount of time, as with a 
meal.  Don't sip it all through the day.

Rinse the mouth with water when finished drinking.

Do not brush teeth for 30 minutes after finishing the lemon water (or any 
acidic drinks).  The enamel is soft at that time and brushing will remove more 
of it.  It takes about 30 minutes for the enamel to return to normal hardness.

So, do drink lemon juice in water to help make the body more alkaline.

                                                                                
                                                     Pat