Most meters have their own specific calibration fluid killernecrox but they are all pretty much the same. 7.01 and 4.01. It is best of you can do a 2 point calibration, if your meter will do it, which will be using both solutions. A one point calibration will only use 7.01. I would recommend you get the fluids for your pen. Normally you can buy the small one use packets that you dip the pen in to for less than a dollar. I have never seen anyone calibrate their pen with distilled water but maybe if you could guarantee it was 7.01 it would work? Honestly, you got me there. I may try it the next time I am going to calibrate mine and do a one point and see what happens. The nice thing about those fluids is you know exactly what they are suppose to be so you can test your pen every few days just to make sure it is in cal without having to actually calibrate it.
Hope that helps!