I neutralize the acidity with a few pinches of baking soda and add water once it stops fizzing. Lemon juice water is very bad for tooth enamel.
Also be sure you are getting certified organic lemons to avoid pesticides (this is true of all fruits and veggies).
Like the other posters noted, adding unprocessed Sea Salt is critical. Water alone will not hydrate your cells and drinking water but still feeling thirsty is electrolyte imbalance easily corrected with adding simple Sea Salt .