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How to Unclog an RV Toilet

Dealing with a clogged toilet in an RV can be especially daunting. There’s no easy way to hire a plumber when you’re out on the road. Plus, drainage problems can escalate quickly when your toilet is two meters away from your kitchen sink.

The bad news is, if you live in your motorhome full-time, your toilet is probably going to clog at some point. The good news is, you can fix it with a little elbow grease and the right tools (rubber gloves definitely included).

As with most aspects of RV-living, preparation makes bathroom blockages much easier to solve. If you’re a full-time RV-er, I strongly recommend keeping rubber gloves, holding tank cleaner, a plunger, a bucket, and a plumbing snake on board at all times for toilet emergencies.

Here are some methods you can use to unclog an RV toilet:

  • Use a plunger
  • Apply a holding tank cleaner
  • Use a plumbing snake
  • Pour boiling water into the tank
  • Try the ice cube method
  • Take it to a dealership
  • Get your hands dirty

This article explores each method in detail to help you eliminate toilet clogs and get back to living your best mobile life. Keep reading for everything you need to know.


What types of RV toilets are prone to clogging?

This article primarily applies to gravity flush toilets as they are the most common toilet in RVs and most likely to clog. Macerator toilets can also develop drainage problems but they’re less likely to because they use motor-powered blades to turn waste into a slurry.

Cassette and portable toilets don’t clog because they’re not plumbed in. These toilets are freestanding commodes with built-in water tanks that are easy to open and close.


What is the right way to empty an RV toilet?

RVs with a standard gravity flush toilet and black water waste tank comes with an unpleasant duty. The waste tank must be emptied regularly so that it doesn’t get overfilled and cause a nasty plumbing problem. It’s not a pretty job but it’s a fact of life for dedicated RV-ers and something that’s surprisingly easy to get used to.

The trickiest part about emptying an RV toilet is locating a suitable dumpsite. Fortunately, as more people are now choosing to live in motorhomes year-round, the number of dumpsites around the country is on the rise. Look for these specialist sites at campgrounds, truck stops, and RV parks.

Once you’ve found a dump site, you’ll need to park your RV close by and connect its sewer hose to the site’s waste line. While wearing disposable gloves to protect you from leaks (no, really), check that the valve on your black water tank is still closed. Unscrew the cap on the black water tank and attach the hose adapter. Now you can safely open the tank’s valve.

When you can no longer hear wastewater rushing through the pipe and into the dump station, the tank is empty. Your RV toilet is ready to get back on the road. Some RVer’s prefer to flush two or three times before disconnecting the hose adapter because it pushes clean water through the system and gives the pipes a rinse.

You’ll need to top up the fresh water and chemicals in the toilet’s holding tank before using it again but, otherwise, you’re good to go.


Is it okay to use the toilet in an RV while it’s on the road?

Provided you’re not the only one on-board, of course, it’s perfectly fine to use a motorhome’s toilet while the vehicle is moving. However, this only applies to motorhomes with engines so only Class A, Class B, and Class C vehicles.

In most states, it’s illegal to even enter a pull-behind camper while it’s being towed because there’s no protection from collisions.


How to unclog an RV toilet

This next section explores some of the strategies you can use to unclog an RV toilet with minimum effort and mess. Some of these methods are very simple. Others might require a longer pitstop and a visit to the hardware store. Below are the steps you need to start unclogging your RV toilet:


1. Use a plunger

The plunger is the quickest and easiest way to unclog a toilet. It won’t always work but it’s always worth a try because plungers are widely available and it takes mere seconds to use them. Unfortunately, plunging is only effective on minor obstructions.

If you’ve got a small clog close to the top of the tank, a moderate amount of suction might dislodge it. So it’s worth a try. If it doesn’t budge, you know you’ve got a more serious obstruction and need to switch to a different strategy.

Clogs that are deep down in a motorhome’s black water tank can’t be fixed with a standard plunger.


2. Apply a holding tank cleaner

A common cause of RV toilet clogs is what’s known as a ‘pyramid plug.’ It’s less fun than it sounds, trust me. Pyramid plugs occur when a black water tank’s valve gets left open and too much water escapes. If you keep flushing into the sewer connection without refreshing the water, a pyramid of waste will start to back up into the bowl.

There’s an easy way to eliminate plugs but the method is time-consuming. If possible, do it before you go to sleep because the toilet will be out of action for several hours.


a. Close the black water tank valve

Make sure the RV’s black water tank valve is closed. If the valve is open, any chemicals you use to clear the obstruction will just drain out.


b. Fill the toilet bowl with water

Before applying a holding tank cleaner, fill the toilet bowl with as much water as possible. Take your time with this and stop if you think the toilet is going to overflow. But the more water you can safely add, the better the result.


c. Pour holding tank cleaner into the bowl

Pour a whole bottle of holding tank cleaner into the bowl. Step aside and give it time to travel into the tank.


d. Let the cleaner sit in the bowl

These cleaning chemicals need a lot of time to work through a blockage. For the best results, do not use the RV’s toilet for at least twelve hours, preferably much longer. Depending on the severity of the clog, you can leave the cleaner in the bowl for up to twenty-seven hours.

This might not be possible without access to a second toilet, so just leave the cleaner to do its work for as long as you can.


e. Drain the tank

After giving the chemicals plenty of time to liquefy the clog, open the black water tank valve. Allow the tank to drain completely.


f. Rinse the tank

Once the tank is empty, rinse away any leftover debris by flushing the RV toilet several times over a twenty-minute period. If your RV has a dedicated toilet rinser, use it. However, for the majority of motorhomes, the rinser doubles up as the toilet’s flush function.


g. Close the valve

When you’re confident the waste tank is empty and the pyramid plug has been flushed away, close the valve. Keep it closed for as long as possible now, opening it only when you need to unload at dumpsites. This will help to prevent more clogs from developing.

NOTE – When shopping for a holding tank cleaner, read the instructions carefully to ensure the product you choose is suitable for an RV toilet. Motorhome toilets are made from different materials than standard house toilets. Chemicals that are too caustic will eat right through a plastic septic tank and cause irreparable damage.


3. Use a plumbing snake

Another tool you can use to unclog your RV’s toilet is the plumbing snake. It’s similar to a plunger but designed to move larger obstructions. As with plunging, there’s a chance it won’t work if the clog is deep down in the tank.

Still, plumbing snakes are handy because they’re inexpensive, widely available in hardware stores, and give you a much longer, much more flexible tool to work with.

Despite having a longer handle, allowing you to stand further back from the toilet bowl – plumbing snakes have a reputation for being messy. The pointed end punches a hole through obstructions. If there’s built-up pressure behind a clog, there could be a spray or splashes of wastewater.

Wear rubber gloves and, if you can, safety goggles to protect your eyes from the bacteria in black water. You’ll also need a bucket.

Consider asking a friend to help with opening and closing the tank while you’re applying the plumbing snake in the bathroom.


a. Position a bucket under the sewer aperture

Ask your helper to position a bucket under the sewer aperture of the RV’s black water tank. The valve should be closed at this point.


b. Drain the waste

When the bucket is in position, they should open the valve and allow as much unobstructed waste to drain out as possible.


c. Use a plumbing snake

Once the flow of water has stopped or slowed to a trickle, insert the plumbing snake into the toilet. This type of tool has a bendable neck so twist, flex and manipulate it through the pipe until you hit resistance.


d. Dislodge the obstruction

When you find the obstruction – you’ll know because the plumbing snake won’t move past it – wiggle the tool every which way to dislodge it. Apply vigorous back and forth movement to break the clog into smaller, flushable pieces.

Again, you’ll know if it dislodges because the resistance will disappear and the plumbing snake will be able to move freely through the pipe.


e. Close the black tank valve

When you’re confident the clog is gone, ask your helper to close the black water tank valve. Keep it closed until you can get to a suitable dump site to empty the offending materials into a sewer.


f. Rinse the tank and refill it

Perform a basic rinsing process. Then, refill the tank’s water and top up any chemicals you use to keep the toilet running efficiently.


4. Pour boiling water into the tank

The boiling water technique is useful if you can’t get a store to buy a holding tank cleaner or another unclogging solution. The goal is the same, to break the obstruction into smaller, flushable pieces.

A common reason for clogs in RV toilets is a shortage of water in the tank. Hot water is a remedy for this because it turns the obstruction into more of a slurry so that it can be flushed much easier. You could use cold water but it’s worth boiling a kettle to add a bit more abrasiveness and break up the clog faster.

Pour the boiling water into the toilet bowl, rather than directly into the tank, to give the whole system a bit of a shock. Flush once to push it through the pipe. Then, allow the hot water to settle and work through any obstructions over the next two to three hours.

Severely impacted clogs may need several attempts before they dissolve. Try it three or four times if necessary. If the clog still won’t move after this many tries, repeat the process with holding tank cleaner or try a different method.


5. Try the ice cube method

The ice cube method is another quick trick you can use to tackle a clog when plumbing equipment and cleaning supplies are scarce. It works the same way as the boiling water technique except you use ice cubes instead of hot water.

Boiling water is more likely to clear a large clog than ice cubes so the best method for the job depends on the severity of the problem. You could try both methods but leave ample time between them if you do. Switching between boiling and freezing water too quickly will put a strain on the pipes and increase the risk of cracks.

A cracked pipe is a very different issue from a clog and will put your RV’s toilet out of action for several days. Make sure you’re working towards a solution and not a costly repair.


a. Fill your toilet bowl with water and ice cubes

Fill a third of your toilet bowl with clean water. Then, add as many ice cubes as you’re comfortable with.


b. Flush the toilet

Flush the toilet and then add more ice cubes. Flush again.


c. Repeat the process

Over the next hour, repeat the process as many times as you can or until the clog disintegrates. If necessary, add more water to help with flushing the ice into the tank.


6. Take it to a dealership

This is the last resort scenario as it’s worth trying all of the methods listed in this article before asking for professional help. The unclogging tips described here might not work on all obstructions but they come with minimal risk. It’s highly unlikely they’re going to make the problem any worse and there’s a good chance at least one will clear the clog in your motorhome’s toilet and get you back on the road.

The downside to professional plumbing services is, of course, their cost. Expect to pay anywhere between $100 to $200 to have your toilet clog removed with a high-pressure tank wand.

It’s definitely worth the cost if you’ve tried everything else and are running out of time and patience with the issue. Though it won’t always be easy to find or get to a dealership while traveling.


7. Get your hands dirty

In an emergency – say you’re days away from the next dealership but need a working toilet immediately – there’s always the most old-fashioned method of them all. The one most of us save for really dire times. Yes, I’m talking about going in manually with very thick gloves and some safety goggles.

Probe as far down into the bowl as you can to see what you can find. It won’t be pleasant and you’ll probably spend the rest of the night washing and rewashing your hands even with the gloves but it might prevent the need for a dealership visit.

The methods you’re willing to use to unclog your RV’s toilet will depend on a variety of factors. When you’re out on the road driving through a lonely stretch of rural countryside, options may be limited. And as long-time RV-ers know, keeping the mobile home healthy and functional is priority number one.

You’ve got to do what you’ve got to do.


How to prevent clogs in your RV’s toilet

Prevention is cheaper (and far less stinky) than the cure. So the best way to deal with clogs in your motorhome’s toilet is to stop them from occurring in the first place.

Here are some things you can do to reduce the risk of obstructions:


1. Keep the black tank water valve closed

The single best way to prevent pyramid plugs is to keep the black water tank’s valve closed as often as possible. Try to open it only when you’re at a dump site or working to clear an obstruction in the pipes.

It significantly reduces the risk of clogs because, when the valve is closed, toilet waste combines with water and other liquids. The materials form a slurry that’s too runny to create a blockage.

When the valve is left open for long periods, liquids flow out of the tank and into the sewer line where they cannot mix with solid waste. The result is a dehydrated mass of material that is much more likely to cause a clog.


2. Use more water for flushing

Another quick trick is to flush twice after solids. This introduces more water to the tank and helps to form that all-important slurry we’ve just been talking about. The problem with this method is it isn’t very eco-friendly. If you’re concerned about water consumption, it might be something you’re uncomfortable doing.

Though I must stress the importance of good toilet maintenance to prevent blockages and the need to use lots and lots of water to remove them. Prevention really is cheaper than the cure.


3. Buy septic-safe toilet paper

Those who are new to motorhome life might not realize toilet paper comes in ‘septic safe’ and ‘non-safe’ varieties. Very thick, double-ply toilet paper tends to be unsuitable for RV toilets. Flushing it can lead to clogs because the material is too dense to get dissolved by the septic tank’s chemicals.

Using toilet paper products labeled ‘septic safe’ is a great way to prevent plumbing problems and keep your bathroom happy and healthy. The thinner the better when it comes to your loo roll. Avoid flushing items like baby wipes because they can gum up the system very quickly indeed.