How to Unfreeze a Frozen RV Sewer Hose

While many glampers are fair-weather weekend warriors, there’s still a substantial number of full-time people in their RVs.

If you’re spending time in your RV throughout the winter months, chances are you’ve had to drain out your septic system in freezing conditions. This creates its own unique set of challenges, one of which is a frozen RV sewer hose.

How RV septic systems work.

An RV has a septic system just like any other home. However, they need to be drained once they’re full due to their size. This means you have some additional valves not found on residential systems and some exposed above-ground sewage lines. In a home, these lines are underground and usually below the frost line.

Full tanks usually aren’t a problem any other time of the year; you find a dump station (located at nearly all RV parks and campgrounds) and dump your gray and black water tanks.

You pull out the sewer hose and attachments, connect to the septic drain on the RV, connect the other end to the in-ground septic tank, and pull the valve. It’s too easy.

But what if the valve is frozen or there’s ice in the RV sewer hose? That’s a problem you don’t encounter with a residential septic system.

What to do if your RV sewer hose freezes.

Frozen Sewer Hose with Black Water
Black water backed up due to frozen sewer hose.

Picture this, you’re a full-time RVer or just a winter-glamper on a chilly weekend, and you have to drain the tanks. You left the hose attached because you drain your tanks every couple of days. Not a problem most of the time, but it’s 20 degrees, and as you pull the drain valve open, you notice the sewage water backs up and stops flowing.

You’re not the first to have a frozen RV sewer hose, so don’t panic.

The only options you have at this point are to hook up a different hose (if you happen to have a spare lying around), wait until the temperature rises to naturally thaw it out, or speed up the process and thaw it out yourself.

One word of advice, though. Don’t touch a frozen sewer hose! If there’s ice in there and you start moving it around, you could break the hose. You’ll have a real mess when the contents begin to thaw out.

How to thaw a frozen RV sewer hose.

The quickest way to thaw a frozen sewer hose is by hot water. Since you’re trying to drain your tanks, that means your gray water is most likely full, and just running hot water in the sink is out of the question. You’ll need another source of hot water.

Disconnect the hose from the camper and pour hot water down the hose. I’m sure the more, the better, but I’ve had success with one gallon of hot water per ten feet of hose.

Once you add the hot water, you’ll need to wait a few minutes to melt the ice in the lines. You can check the end of the line to see how much water is draining. When you see the rush of water, you’re good to go and can start draining your tanks.

Of course, getting to this point is not the most desirable. As they say, an ounce of prevention is worth a gallon of remedy.

Prevention tips for a frozen RV sewer hose.

Continuous Slope of Septic Hose
Photo courtesy of the RV Geeks

The best way to deal with a frozen RV sewer hose is to avoid them. Here are a few practical tips that will help you avoid these situations.

  • Stow your lines between uses. This mainly applies to weekend warriors or those with their RVs in storage. If you don’t need the hose right now, put it away until you need to drain your septic tanks.
  • Pour RV-grade antifreeze in the lines. Full-timers usually keep their hoses connected. If that’s the case, add one or two cups of RV-grade antifreeze in the pipes. Be sure to use antifreeze that’s rated for RVs and marine equipment as it’s usually septic-safe.
  • Make sure there is a constant slope in your lines. If there’s no water in the pipes, there’s nothing to freeze. Maintaining a continuous pitch without any dips in the lines will ensure that the water is out of the lines before it can freeze.

What about frozen septic tank valves?

Another component that often freezes is the valves under the camper exposed to the elements.

Since you can’t stow these pipes and valves because they’re fixed to your camper, you’ll have to insulate them. We’ve included a quick video showing exactly how to protect your exposed pipes/valves to prevent them from freezing.

Spoiler: It’s super easy to prevent your tank pipe and valves from freezing. All you need to do is wrap them in foil tape, then wrap-on pipe heating cable, then fiberglass pipe wrap.

Keep your Sewer Hose Functioning Properly.

Winter glamping in an RV is quite an adventure, but make sure you’re prepared to deal with mother nature. Of course, the best way is to be ready and avoid frozen RV sewer hoses altogether, but that’s not always possible.

Don’t stress over it if you find yourself in such a situation. Wait it out or pour some hot water in the line, and you’ll be back in business.

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