I made preserved lemons, topping off the lemons with water, according to recipe. Paula W. says "never!" Should I throw out the water with the juice?

I was wondering, why are we never topping it up with water? Do we not add enough salt to kill/retard the unwanted bacteria or is it something to do with the way city tap water is treated?

I'm assuming you didn't boil the water first? You can probably use the boiling method, described here in Bon Appetit. http://www.epicurious.com/recipes/food/views/preserved-lemons-51187340. Boiling the water will prevent bacteria from forming.

if you have more lemons, i'd drain and start over, fill the lemons with salt again then fill to the top with fresh lemon juice. if not in a rush (and i dont see how you can be since they need at least 2 weeks anyway), go buy some more and start from scratch. i love preserved lemons, they're worth the little effort and the long wait as long as they're good.