Getting ready for the off-season usually starts with blowing out camper water lines so you don't end up with a mess of burst pipes when the ground thaws in the spring. It's one of those chores that every RV owner dreads a little bit the first time they do it, but once you get the hang of the rhythm, it actually goes pretty fast. If you've ever dealt with a cracked plastic fitting hidden behind a cabinet, you know exactly why this is the most important part of winterizing.
The whole goal here is simple: get every single drop of water out of the plumbing system. Since water expands when it freezes, even a tiny amount left in a bend or a valve can cause enough pressure to snap the line. Using compressed air is a favorite method for many because it's clean, relatively cheap, and you don't have to spend all spring flushing out the taste of "pink stuff" from your faucets.
What You'll Need to Get Started
Before you even touch a faucet, you need a few specific tools. You can't just shove an air hose into your city water inlet and hope for the best.
First, you're going to need a blowout plug. These are small, inexpensive brass or plastic adapters that screw into your city water intake. One side has the hose threads, and the other has a valve like a car tire (Schrader valve) or a quick-connect fitting for an air compressor.
Second, and this is the big one, you need an air compressor. It doesn't have to be a massive industrial unit, but it does need to have a tank so it can provide a steady flow of air. However—and I can't stress this enough—you must have a pressure regulator. Most RV plumbing is rated for about 40 to 50 PSI. If you hook up a compressor set to 100 PSI and let it rip, you're going to blow out your seals and fittings along with the water. Set that regulator to about 30 or 40 PSI just to be safe.
The Pre-Blowout Checklist
You don't want to start blowing air through the lines until you've cleared the bulk of the water manually. It's just easier on your equipment.
Start by draining your fresh water tank completely. Most campers have a white drain valve underneath. While that's running, go ahead and empty your gray and black holding tanks at a proper dump station. It's never a fun job, but it's a lot less fun if you forget and find a "frozen surprise" in your sewer pipe come January.
Once the tanks are empty, find your low point drains. These are usually two pipes (one red, one blue) sticking out the bottom of the camper with caps or valves on them. Open those up and open every faucet inside the camper to let gravity do its thing. You'll be surprised how much water just pours out on its own.
Don't Forget the Water Heater
This is the step where people usually make a mess. You need to drain the water heater separately. Make sure the water heater is turned off and the water has cooled down before you touch it. If it's been running, that water is under pressure and it's hot.
Unscrew the drain plug or the anode rod (usually located behind the exterior access panel). When you pull that plug, stand back—the water is going to gush out. Once it's empty, it's a good idea to flip the bypass valves on the back of the heater. You don't really need to blow air through the water heater tank itself; you just want to clear the lines leading to and from it.
The Process of Blowing Out the Lines
Now that the bulk of the water is gone, it's time for the air. Screw your blowout plug into the city water inlet and connect your compressor. Make sure all your faucets are closed before you turn the air on.
- Turn on the compressor: Let the lines pressurize up to your regulated 30-40 PSI.
- Start with the furthest faucet: Usually, this is the kitchen or the bathroom. Open the cold side first. You'll hear a lot of sputtering and see mist spraying out. Keep it open until nothing but air is coming out.
- Switch to the hot side: Do the same thing. Even though the water heater is bypassed, there is still water sitting in the hot water lines throughout the camper.
- Repeat everywhere: Move to the next closest faucet, then the shower, then the toilet.
Don't forget the "hidden" water spots. If you have an outside shower, a spray port, or a kitchen sprayer, those need to be blown out too. The toilet is especially important—hold the flush pedal down until you don't hear any more water gurgling in the valve.
Checking the Low Point Drains Again
After you've gone through every faucet, I like to go back outside and open the low point drains one more time while the air is hooked up. Sometimes a little bit of water gets pushed back into those low spots during the process. Once you see nothing but a fine mist or clear air, you're in the clear.
The Debate: Is Air Enough?
Some people stop right here and call it a day. If you live in a place where it only dips a few degrees below freezing, blowing out camper water lines is usually plenty. But if you're in the North where temps stay below zero for weeks, you might want a little extra insurance.
Even with a good compressor, tiny droplets of water can settle in the low spots of the P-traps (the U-shaped pipes under your sinks) or in the water pump itself.
I always suggest pouring about a cup of RV antifreeze (the pink stuff, not the green stuff for cars!) down every drain. This protects the P-traps from cracking. Also, don't forget the city water inlet check valve. Sometimes a little water gets trapped right behind that screen. With the air pressure off, I usually give that little center button a quick poke with a screwdriver to make sure no water is lingering there.
Final Touches for Peace of Mind
Before you lock up the camper for the winter, take a quick walk-around. Did you remember the ice maker in the fridge? Did you run the water pump for a few seconds to clear its internal diaphragm? (Actually, it's best to disconnect the input side of the pump and let it run dry for a moment to be sure).
It sounds like a lot of steps, but once you've done it, the whole process takes maybe 30 to 45 minutes. It's a small price to pay to ensure that your first trip in the spring isn't spent at the hardware store buying replacement plumbing parts. Just remember: keep the pressure low, be systematic, and double-check every single tap. Your future self will definitely thank you when you're de-winterizing in the sunshine instead of mopping up a flooded floor.