Rotten Egg Smell in RV Camper – Causes and Solutions

If you have ever smelled it, you know exactly what I’m talking about. It’s acrid and nauseating. It will have you jumping out of bed in the middle of the night. When it hits you, you immediately know something is not right. 

This memorable smell can come from a few things, some being far more dangerous than others. No matter the root cause, you need to take care of it right away. 

If you have discovered a rotten egg smell in your camper trailer or RV, it could be caused by leaking gas/propane, your hot water heater, a bad battery, your black tank vent, your toilet, an exhaust fan, or your freshwater tank.

Let’s take a look at the exact causes and how you can fix the issue.

What Causes a Rotten Egg Smell in an RV?

Gas/Propane

Your propane fuels the production of hot water, runs your refrigeration when not tied to electricity, and also powers your stove. You may also use it for other things as well, depending on how your RV is set-up.

RVs equipped with heating will also run propane. These tanks are mounted on the bumper of bumper tow travel trailers and they are welded into place underneath the chassis of Class A, B, and C motor coaches. 

A gas leak can cause a rotten egg smell. This can be leaking from the connection at any of the appliances, or from your bottles if you have a travel trailer. 

The first thing you need to do is open all of your windows. Then shut your gas off at the valve located on your tank.

Turn it all the way off until you are able to locate the source of the leak. This is a major fire hazard. The slightest spark can ignite the fumes.

To check for leaks, you can use some dish soap mixed with water in a spray bottle. Spray it directly on each connection. Bubbles will be the indication that you’ve found your leak.

If you can tighten your connection, recheck to make sure you’ve sealed the leak. If you don’t have a spray bottle handy, smear some soap from your finger directly on the connections and it will also bubble when leaks are present. 

Propane is a liquid gas and will fall when it escapes. This means that it will smell stronger near the floor and more noticeable only when you are laying down if the leak is small. The problem is it can accumulate until a spark ignites that gas. 

Why does propane smell like a rotten egg? It’s actually a smell that is added to propane so you’ll know when there is a leak. Otherwise, it would be odorless and you’d have no idea there was a problem. 

Hot Water Heater

Bad Water

Your hot water heater can cause a smell too. Sometimes it is simply a matter of bad water in your tank and you need to drain it out. You may need to service your hot water heater and flush it out thoroughly. 

Make sure your pilot is off and your cold water inlet valve is shut off. Then drain your heater completely. Unhook your cold water inlet line and pour a few cups of peroxide into your tank and then fill it back up with cold water. 

Let it sit for a few hours. Then open your cold water line back up and turn the hot water on at your kitchen sink and your shower. This will allow the peroxide to work through your system and clear all the lines of the smell.

Let it run long enough to empty the entire tank and refill with clean water from a source you’ve checked and know has no smell. 

Anode Rod

You may also need to replace the sacrificial anode rod. Not all tanks have one, but if yours does, it may need replacing. If this is a job you don’t know how to do, it may be wise to take it in for servicing, especially if you’re still under warranty. 

How to Replace Sacrificial Anode Rod

1. Turn off water and fuel supply lines to the heater

2. Drain about 10% of your tank’s total volume. Most RV tanks are 6-gallon tanks. Drain a half a gallon and you’ll be fine.

3. Find the hex head on top of your tank and remove it. You may need to use a cheater bar and once you remove the hex nut, you’ll be able to pull the anode rod out.

4. Install your new rod, making sure you use plumber’s tape on the threads before doing so. Tighten it by hand until you can’t turn it anymore.

Give it one final quarter turn with your wrench. You don’t want to even move the heater. If you move the heater, you’re tightening too much.

5. Replace your top and you are all done. Again, you may not be comfortable doing this or it may be too difficult for you. The hex nut can be really tight. 

*In some heaters, there is no hex nut and you need to remove the entire top of the heater. 

Battery

RV batteries can smell like rotten eggs when they boil dry and are ready to blow up. This is a very dangerous situation.

The sides of the battery may bulge to the point it explodes, and if it does, battery acid could go all over the place. They can explode with some real force. 

The reason they smell like rotten eggs is the battery is filled with sulfuric acid and water. When the battery gets low on fluid, it can boil.

When that happens, you’ll smell the fumes which are primarily sulfuric acid. It’s apparent as soon as the batteries run low. If you catch it right away, you can save your battery. 

To solve this problem, you’ll need to use some care. Definitely use eye protection when you are working with your battery.

Make sure that you ventilate the area so that the rotten egg smell dissipates. The fumes can be hazardous to breathe. Work with your battery in a well-ventilated area as well.

If the battery has any bulges or signs of swelling, do NOT attempt to fill or charge. Dispose of it properly and very carefully. The cells have become corrupted. 

Black Tank Vent

It could be a venting issue with the black tank. All black tanks have a built-in ventilation system because waste produces gas. When the tank doesn’t vent properly, those smells will back up through your toilet and cause some very noxious fumes inside your RV. 

The main reason this situation happens is that you’ve allowed your black water tank to get too full. It’s always a good idea to never let your tank get over ¾ full due to those gasses that build-up and cause those odors. 

To rectify the situation, empty your tank as quickly as possible and flush plenty of fresh water through it. You may need to run some chemicals for toilet odor through your tank as well.

When you’ve completely rinsed your tank, before using it you should always add some fresh water to the bottom of it and add a packet of RV septic system treatment. 

Toilet

Some toilets, like the Dometic 300, have a defect reported by some folks that cause the smell. If you have the Dometic 300 toilet, which is all plastic, it may be worth swapping it out with a Dometic 310, which has a porcelain bowl. Some people have said this has fixed the smell issue. 

Exhaust Fan

If you are running your exhaust fan when flushing, you could be drawing exhaust fumes back into your rig. While this isn’t guaranteed to stop your issue, it’s a free solution when it works, so why not give it a whirl?  

Fresh Water Tank

Your freshwater tank and lines could be growing bacteria that cause the smell. If you notice it when you are doing dishes and running water at your kitchen sink, this is likely the problem. 

Your solution is to:

1. Empty your tank.
2. Fill with fresh water and 2 cups of bleach.
3. Run that solution through all of your lines until your gray holding tank is emptied (ideally, you are connect to sewer when you do this).
4. Flush the system with fresh water in the same fashion, several times. 

Conclusion

These are generally most of the issues that could cause a rotten egg smell in your RV. If you’ve checked them all and the problem is still persistent, it may be wise to take your rig in and have it checked out by a professional. You definitely want to be safe. Always be cautious. 

The worst thing you can do is ignore the smell. Even if it is a minor issue that is not life-threatening (as far as you know), the issue may get worse.

Take care of it and get back to enjoying life in your RV as soon as you can. Adventures are waiting to be had!