First open any faucets and anything else the electric water pump might be connected to and drain the water pump dry. Next pump RV regulated anti-freeze in to the pump but make sure it is RV anti-freeze. Once the water pump has some anti-freeze in it turn on each faucet one by one and let the faucet run until you see the color of your anti-freeze coming out and proceed to shut them off, also poor some anti-freeze into the toilet and then flush it down then poor a little more in there and leave it set. After that is done you should consider spraying fogging oil in to the intake and generator of the RV this will help protect some vital components of the RV throughout a long winter store. And just like all items that you store for the winter you should always take your battery out and store it inside or for best results of a good healthy spring start up you could leave the battery in the RV but only if you will be able to start it up about once every two to three weeks for about three to five minutes, this will keep all parts moving and in motion and will really help from any unwanted seizing or real slow starts in the spring. Last but not least always give the RV a complete clean inside and out especially any food or crumbs or anything that can go bad if unoccupied for months at a time.