Blowing the lines is risky because you cannot get the water out of the 12v water pump. Best method is to put 4 gallons of pink antifreeze into the fresh water tank. Turn the bypass settings so that antifreeze bypasses the water heater. Pump the antifreeze through all faucets until it turns pink. Run enough water to fill the 'P' trap. Run it through the shower and the outside shower. Run some into the toilet and leave about an inch above the drain. With that done - you're done. Protected for the winter. Quick & easy. Come springtime pump all remaining antifreeze out of the fresh tank. Fill with fresh water and pump it all through the water system to clear out the antifreeze. Drain and refill fresh tank until all antifreeze is gone. Done. Enjoy the 2016 camping season.