Thanks all.... I'm ignoring all the comments about water quality, towing, or boon-docking. We're weekenders, and our site always have electric and usually have water.
It sounds like the main reason that folks advocate using the fresh water tank instead of city water is the eliminate the possibility of a leak or other water intrusion when you're away from the site.
But wouldn't you have to turn off your water pump when you leave, to avoid the same issue?
Seems like the same difference to me -- turning off the city water nozzle or turning off the pump.
Or am I missing something obvious?