A common highschool chemistry example for the polarity of water is the experiment where stream of water is deflected under the influence of a charge (electric field).
Now I have come across some condradicting claims, namely this Youtube video from Veritasium https://youtu.be/1Xp_imnO6WE?t=109 (from around 1:50) and more importantly this publication from ACS http://pubs.acs.org/doi/abs/10.1021/ed077p1520.
These sources suggest that this phenomenon is not based on the polarity of water but charged impurity ions in the water stream. They also claim that the electric field could also only re-orient the molecules, but not deflect them as the electric field also has an opposite effect on the other side of the dipole. This has been bothering me and it is hard to find concluding evidence either way. What are your thoughts?