Wouldn't know...never went that long.
51 hours from the AD 2011 Pennsylvania "Halloween Snow"
54 hours from Tropical Storm Irene
97 hours from Tropical Storm Isabel (AD 2003).
That one got really tedious because I did not have a generator...but I got one right afterward.
Costs about $5.00 for LPG but on a well no electricity = no water.
I was out for approx. 2 days after Irene and 9 days after the 2011 Halloween storm in Northern CT.
Storm Sandy resulted in a 6 hour outage and several brief 10-20 second outages.