not that I do it now, but I have 150 gallons fresh water, and 50 black, 50 gallon grey, so I could in theory dump the grey which I do in Utah becasue of showers etc it fills like in 3-4 days and then we still have 3 days or so of filling the grey when we do come home I do as you mentioned above.. Just a reason why you might be tempted is all