4.  You piss the neighbors off when there are water restrictions in place  (snicker)
We have metered water but have yet to exceed our allotted usage.  For my potted flowers I have a 10 gallon plastic drum that I keep diluted with miracle grow.  In the summer months I have to add to it almost daily and I tell myself that the chlorine and other water plant additives dissipate because of being exposed to air and trapped in a container.   
We can always fool ourselves  lol