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The natural, piney scent of the Great Outdoors just steps from your RV is muddled with something else: a foul, harsh, disturbing odor. Unnervingly, your RV has a sewer smell emanating from its depths. This is the smell that nightmares are made of, and you can’t tell where it’s coming from or what to do about it.

Why does the outside of my RV have a sewer smell?

3 main reasons for a sewer smell outside of your RV could be due to the blackwater tank, greywater tank, or an overcharged battery.

In this article, we will dive into these causes and provide you with DIY solutions to rid your home on wheels of that foul odor.

Speaking of stinky questions, here are some related articles that may be helpful for you:

Why is There a Sewer Smell Outside my RV?

RV sewer line hooked up at campground
RV sewer line properly hooked up at the campground

The most common causes for a sewer smell outside your RV are typically due to a problem with either the blackwater tank or the greywater tank. The smell may also be caused by an overcharged battery.

However, some other sources could give off a similar funk. Keep reading to jump right into the details of the stinky situation you’ve found yourself in.

Top 3 Reasons For A Septic Smell

To keep things simple, we have chosen the three most plausible reasons as to why you are experiencing that smell, and they include… (drumroll, please):

  1. Blackwater tank.
  2. Greywater tank.
  3. Overcharged battery.

Let’s dive into these, shall we?

Problems with the Blackwater Tank

First of all, it’s important to understand that when we use the toilet in our RV – no matter which “number” we do – all that waste goes to the blackwater tank. It holds all the waste that comes from the toilet until you can adequately empty it at a sewer dumping station. Your RV blackwater tank will always slightly smell like a septic tank if you’re close enough, but it shouldn’t be that noticeable.

While we’re on the subject, keep in mind that the waste coming from the bathroom should be biodegradable, whether solid or liquid. Always ensure that the toilet paper used is septic or RV safe.

Now, considering the function alone of this tank, it’s already a primary suspect. Each of the holding tanks in your RV has a valve which you use to either refill or empty the tank’s contents, depending on which tank it is. Your RV comes with a built-in blackwater tank flush system. This system includes an inlet valve that allows you to pump water into it. To see if your blackwater tank is the culprit, check for the following:

  1. Loose dumping valves. During emptying at a dumping site, it is possible that the valves were not properly tightened afterward. It can lead to leakages when the tank starts filling up again, producing a foul odor outside the RV.
  2. A bad dumping valve. It either no longer tightens properly or loosens with time. This also will lead to leaks.
  3. A crack in the tank. There should be waste content or just water in the tank to check for a tank crack. Carefully inspect the tank, looking for wet spots as the crack may not be immediately noticeable depending on how big it is.

Next, we’ll discuss similarities between your blackwater and greywater tanks.

Problems with the Greywater Tank

Equally important as the blackwater tank, the greywater tank is another holding tank in your RV. This one contains everything from the bathroom sinks, kitchen sinks, and water from the tub or shower. Food particles coming from your kitchen sink are biodegradable and can emit very foul odors when degrading.

The greywater tank also has a valve for emptying its contents at the dumping station. As with the blackwater tank, you’ll want to check the following:

  1. Check the valves to see if someone didn’t appropriately tighten them after emptying.
  2. Check to see if the valve of the tank is bad and is causing leakage outside.
  3. Check for cracks in the tank.

Finally, we will detail how to troubleshoot an overcharged RV battery.

Overcharged Battery

Many RVs use lead-acid batteries which store electricity instead of making it. For this reason, they contain lead and a liquid electrolyte composed of water and sulfuric acid (a form of hydrogen sulfide).

As a result, accidentally overcharging a lead-acid battery can cause this electrolyte to give off hydrogen and oxygen gases. These gases produce a pungent odor very similar to that of a sewer or rotten eggs.

To check for an overcharged battery, do the following:

  1. Check for overheating. Wear a glove to do this to prevent getting burned by electrolytes that may have leaked.
  2. A soundcheck. It usually has a simmering, bubbling, or boiling sound.
  3. A smell check. It should be the most obvious as the sewer smell will be strongest at that point.
  4. A swollen battery is also an indicator.

How Do You Fix A Sewer Smell In An RV?

Now that you know the three main causes of stinky RVs, you want to know how to fix them, right?
Rest assured, we have provided viable solutions for each of the issues above.

How to Fix RV Holding Tanks With Septic Smell

This fix applies to both your black and grey water tanks alike.

Loose dump valve: For a loose valve, simply tighten it and ensure that the valve is not faulty.

Faulty dump valve: After figuring out which tank valve is defective, you can use the following procedure for those that want to “DIY” it.

But first, you will need these essential tools:

Protective gearNitrile (waterproof) gloves, eyewear, and a respirator or dust mask for those with sensitive noses or a weak stomach.
LubricantPetroleum Jelly, WD-40.
Cutting toolHacksaw. This is for rusted nuts or screws that are difficult to loosen.
Loosening and tightening toolFlathead or Phillips head screwdriver, wrench. (Type depends on what kinds of screws or nuts are in place)
Two containersBucket, empty storage container, a can, etc.

Steps to Fix a Faulty RV Dump Valve

  • First, measure the diameter of your RV sewer pipe to determine its size as you may need to purchase extra piping. The diameter could be either 1.5 inches or 3 inches.
  • You may also need to purchase a new valve. This should come with the T-handle and extension rod. Be sure it does to be on the safe side. There are many different types of valves, so you can work within your budget here.
  • Second – be sure to wear a pair of waterproof gloves! You want to prevent waste from the tanks getting on your hands and avoid having a deep desire to burn your hands off.
  • Next you’ll want to place a bucket or empty container (preferably one that won’t be used by you or others again) beneath the junction where the pipe and valve join. Another bucket should be kept where the extension rod is. You will remove this piece, and wastewater could drip out.
  • The dump valve rests about 5 to 11 inches behind the sewer line where you dump your waste.
  • The tank should be adequately drained and flushed to remove any waste beforehand. It can be done multiple times if you want the system cleaner.
  • Then, using the appropriate tool, unscrew the bolts holding the dump valve in place. They are on the corners of the rectangular-shaped valve.
  • After the screws are removed, slip the old valve out and lift the entire piece out by hand. Some come with their two circular flanges pre-lubricated; if they aren’t, then apply a generous amount of petroleum jelly to protect it when installing.
  • Read the instructions the valve came with, as some may not require lubrication.
  • The new dump valve comes in two parts with two round flanges meant to fit into each other. The flanges fit around each pipe connection on the dump valve’s sides to minimize friction between the dump valve and the sewer pipes.
  • Place your valve together and slide a flange over each pipe connection. Take the two halves of the valve and hold them together so that the pipes’ openings point away from the center. Then, slide the flanges over the two pipe connections.
  • Place the new dump valve between the waste pipes. Take the two halves of the valve and place them between the lines where the faulty valve was previously attached. Push the two tubes against the dump valve on both sides so that the pipes are flush with the valve’s openings.
  • Compress the valve and two pipes together. Ensure you line the screw slots on the valve up properly with the screw slots on the pipe frame. You should do it correctly to avoid any gaps that will cause a leak.
  • Concentrate during this step to give room for the extension rod to pull out.
  • Finish installing the valve by tightening the screws in place. Ensure to get a tight fit.

What to do After Replacing a Broken Valve

  • Do a check by running water or flushing an empty toilet to ensure your new valve isn’t leaking.
  • Carefully empty the bucket used during the installation into a septic tank marked out for dumping or flush it down your toilet.
  • Dispose of your gloves properly after you’re done by putting them into a plastic bag and tying or sealing the handles. Wash your hands thoroughly (with a disinfectant soap) under running water.

What To Do if Your RV has a Cracked Tank

In the case of a cracked tank, you should do the following:

  • Avoid using the toilets, sinks, and showers until the tank is fixed. Look for other alternatives like the campsite’s bathroom and toilets or mother nature herself.
  • Use a bucket or an empty container to collect any leaking fluids.
  • Dig up any areas that the contents of the tank may have spilled into.
  • Shovel contaminated dirt into a heavy duty trash bag and dispose of accordingly.
  • In any event, the best advice is to replace the tank. Unfortunately, we don’t all have a spare $250 – $800 lying around. The next best thing to do is fix it. A note of warning, though…there’s always the possibility of a fix failing.

What Does an Overcharged RV Battery Do?

An overcharged battery not only smells bad but is also very hazardous to both human health and the environment. It can lead to an excessive release of hydrogen, oxygen, and hydrogen sulfide gases into the surroundings.

This might get a few unpleasant reactions from the neighbors at your campsite.

It is vital to know if your battery is emitting hydrogen sulfide. Before reaching toxic levels, hydrogen sulfide may smell like sewage or rotten eggs. However, once it reaches acutely toxic levels, the gas can impede a person’s ability to smell its distinctive odor and may rapidly lead to unconsciousness.

When mixed in the air at the right levels, hydrogen sulfide can explode on contact with fire – a notorious campsite guest. Thus, the indicative “rotten egg” smell is more friend than foe here.

How to Fix an Overcharged RV Battery to Remove Septic Smell

To mitigate this, do the following:

  • Wear protective gear! Eyewear, face shield, respirator, and acid-resistant hand gloves. You do not want to inhale or touch burning acid.
  • Ensure no fire source such as a campfire, grill, lighter, cigarette, etc., is around the area to avoid an explosion.
  • Disconnect the battery from its charger and gently lift it from its compartment.
  • To neutralize any spilled acid, use a neutralizing agent such as lime. If you don’t have any, one pound of soda ash or baking soda per gallon of water is a good alternative.
  • Make sure that the area surrounding the spill is completely neutralized as well. If you have any, use absorbent material like cat litter or absorbing clay to neutralize the area.
  • Keep used materials in an acid-resistant container or bag and store them away until you contact authorities to properly dispose of them.
  • Lastly, replace the battery with a new one.

Frequently asked questions (FAQ)

Can I put bleach in my RV holding tanks?

Yes, you can. Bleach kills harmful microbes in the tanks and is, therefore, a good sanitizing agent.

Does overfilling RV tanks cause leaks?

Yes, an overfilled holding tank can cause leakages, and the tanks should be emptied and monitored to ensure that was the cause.

Can I still use an overcharged lead-acid RV battery?

No, you should not reuse an overcharged lead-acid RV battery. An overcharged battery is no longer usable and should be disposed of properly.


While the causes mentioned above are likely culprits of a sewer smell outside your RV, they aren’t necessarily the only ones. Leaking propane tanks, busted sewer pipes, or even nearby natural hot springs can all cause a septic smell. So, if you have checked all of the causes in this article and not located the scent source, try looking towards those other options. Are there other causes you can think of? Do let us know.

In conclusion, whatever interesting or mundane encounters have happened during your travels, it is a great idea to bring along an RV Journal and planner to help you keep track of your journeys. Check our Etsy store and print some off today!

Here are some other articles that may help answer your questions about RVing:

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    Shauna Kocman founder Family Travel Fever
    Shauna Kocman founder of Family Travel Fever

    Hi, I’m Shauna – Welcome to Family Travel Fever.  We are a large family, that was bitten by the travel bug!  We travel with kids and extended family.  I take the kids by myself sometimes because I don’t mind flying or driving solo with my crew to discover the coolest places.

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