First, to avoid plumbing problems due to freezing temps this winter. We recommend you use a compressor with a fitting that we stock in the store (see the picture). It screws into your city water fill. Set the compressor at 55 psi, and while pressurizing the system, have someone open each faucet one by one and depress the toilet pedal or hand flush to blow all the excess water out of the system.
We recommend this method over adding RV anit-freeze to the system because if you want to use the RV in the winter, you will not have to flush the system; you add water and are off on your RVing adventure.
Also, you can add a little RV anit-freeze to the traps and make sure that your holding tanks are mostly empty. Also, pull the low point drain to your fresh water tank. One last thing is to drain your water heater, and if it is tankless, you will want to check your owner's manual to see how you drain the copper coils. Make sure if you use RV anti-freeze to bypass your water heater. If not, you will get a horrendous odor that you will never be able to get rid of.
