Blowing water out of RV lines is easily one of the most important things you can do to protect your rig before the first deep freeze hits. If you've ever dealt with a burst pipe or a cracked plastic fitting hidden behind a cabinet, you know exactly why we go through this trouble every year. It's not just about avoiding a mess; it's about saving yourself thousands of dollars in repair bills and a whole lot of heartbreak when you try to de-winterize in the spring.
I've met a lot of people who are intimidated by the process, thinking they need to be a professional plumber to get it right. Honestly, it's pretty straightforward once you understand the logic behind it. You're basically just using air pressure to push every last drop of water out of the plumbing so there's nothing left to expand and crack your pipes when the temperature drops below freezing.
Why air is often better than just antifreeze
There are two main ways to winterize an RV: the "pink stuff" method (pumping RV antifreeze through the whole system) and the air method. While many people use a combination of both, blowing water out of RV lines is my preferred starting point.
First off, it's a lot cleaner. If you rely solely on antifreeze, you have to spend a significant amount of time in the spring flushing that stuff out of your lines. Even after several flushes, you might still get that weird chemical smell or a lingering funky taste in your drinking water for the first few trips of the season. By using air to clear the lines, you use much less antifreeze, usually only needing it for the P-traps and the waste tanks. It makes the spring startup way faster and much more pleasant.
The gear you'll need to get started
You don't need a massive, industrial-sized shop compressor for this, but you do need something more substantial than those tiny 12V tire inflators meant for emergencies. Those little pumps just don't move enough volume of air to get the job done effectively.
Here is the short list of what you should have on hand: * An air compressor: Anything with a small tank that can maintain a steady pressure will work. * A blowout plug: This is a small, inexpensive brass or plastic fitting. One side screws into your city water inlet, and the other side has a connection for your air hose. * A pressure regulator: If your compressor doesn't have a reliable built-in regulator, get one. You must control the PSI. * A wrench or socket set: Usually needed for the water heater drain plug.
Setting the right pressure is crucial
Before you even hook up the hose, let's talk about pressure. This is where most people get nervous, and for good reason. If you blast 100 PSI into your RV's plumbing, you're going to blow a seal or a connection, and you'll have a leak long before the ice even forms.
Most RV plumbing systems are designed to handle about 40 to 50 PSI. When I'm blowing water out of RV lines, I usually set my compressor regulator to somewhere between 30 and 40 PSI. That's plenty of power to push water through the lines without risking damage to the delicate plastic fittings or the water pump valves.
Prepping the system before the air starts
You can't just hook up the air and call it a day. You have to prep the system first. Start by draining your fresh water tank and your gray and black waste tanks. It's much easier to do this at a dump station while you're still out on your last trip of the year.
Next, you need to deal with the water heater. This is a big one. Never try to blow out the system while the water heater is full and the bypass valves are open. It just won't work well, and it takes forever. Turn off the water heater (both electric and gas) and let it cool down. Then, unscrew the drain plug or remove the anode rod. Stand back, because a lot of water is about to come rushing out.
Once the water heater is empty, flip those bypass valves. You want the air to skip the heater tank entirely and go straight through the hot and cold lines.
The step-by-step blowout process
Now for the main event. Screw your blowout plug into the city water inlet and connect your air hose. Make sure your compressor is pressurized and regulated to that 30-40 PSI range we talked about.
I like to start with the faucet furthest away from the inlet and work my way back. Here's how you do it:
- Open the kitchen faucet: Start with the cold side. You'll hear some sputtering and see mist. Keep it open until nothing but air comes out. Then do the same for the hot side.
- Move to the bathroom: Open the sink faucet, cold then hot. Again, wait for that steady stream of air.
- The shower is next: Don't forget the showerhead! I usually take the showerhead down and let the hose hang low so gravity helps the water out.
- Flush the toilet: This is the one people often forget. Hold the flush lever down until you stop seeing water and only hear air. This clears the valve, which is notorious for cracking if it holds water.
- Low point drains: Most RVs have "low point drains" hanging underneath the rig. Open these up one at a time while the air is running. You'll be surprised how much extra water was hiding down there.
Don't forget the "hidden" water spots
Even after you think you're done, there are a few sneaky places where water loves to hide. If your RV has an outside shower, make sure you blow that out just like the interior ones. If you have a black tank flush connection, you should briefly blow air through that as well to clear the internal spray head.
If your rig has a washing machine or an icemaker, those require a little extra attention. Usually, you have to run a short cycle to pull air through those specific valves. If you aren't comfortable with that, that's where a little extra RV antifreeze comes in handy to make sure those specific lines are protected.
The final touch: Antifreeze in the traps
Once you've finished blowing water out of RV lines, you're about 95% of the way there. However, the air won't clear the P-traps (the U-shaped pipes under your sinks) or the toilet bowl seal. These need liquid to keep sewer smells from coming up into the living space.
Pour about a cup or two of the pink RV-specific antifreeze down each drain—kitchen sink, bathroom sink, and shower. Then, pour a little into the toilet and flush a bit of it down to protect the seal, leaving a small amount sitting on top of the blade valve to keep the rubber from drying out over the winter.
Checking your work
After you've gone through every faucet and drain, I usually like to do one more quick round. It only takes a minute to walk through and crack each faucet open one last time. Sometimes water can settle in low spots, and that second blast of air catches the stragglers.
It's a satisfying feeling when you hear that pure "hiss" of air with zero mist. That's the sound of a job well done and a lot of money saved. Honestly, once you get the hang of it, the whole process of blowing water out of RV lines takes less than half an hour. It's a small price to pay for the peace of mind you'll have all winter long, knowing your rig is safe and dry, just waiting for the first warm day of spring.