It depends on what was used to winterize the unit. Being it was a dealer I would assume they used an RV antifreeze. If so its a non-toxic product but, you need to flush the water system. First remove your inline water filter (if you have one on your unit. Then connect a fresh water line to your RV intake. Turn in on and open the faucet at the furthest distance from the intake. First open the cold side. let it run until the antifreeze (usually red in color) flushes clear. The open the hot water side and do the same. The go to all outlets in your unit and allow the to flow clear also. You may need to open your grey water tanks and dump them prior to your travel, because they will most likely be full. It take several gallons of water to flush the four to five gallons of antifreeze that was placed in your system. When you have flushed the lines completely, then replace the water filter. Hope this helps.