That was probably your low point drain on your plumbing system. Removing two caps should drain your fresh and hot water pipes, the water heater usually has to have a plug removed for it to drain. I always drain my water heater, I don't like the thought of water setting in their for 3 or 4 weeks till I can get out again. If your water heater is empty you will need to start your water pump in order to fill the heater tank which you should do as soon as there is a few gallons in the fresh water tank.Your water heater probably holds 6 gallons of water, so if you fill your tank, remove the hose and then turn your pump on you will lose 6 gallonsof your fresh water right away just to fill the water heater. Does that make sense? Did I explain that in such a convulated way that I made it hard to understand?
F250-7.3 L, 2012 305SK--Happy Wife, Good Life