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We can’t track a scent for days like a bloodhound or see an object from 2 miles away like an eagle, but one thing is sure, we can tell when something smells wrong.

The usual scent outside your RV is now mixed in with something else, a foul, harsh disturbing odor. More specifically, your RV has a sewer smell outside, and you can’t tell exactly what the cause is. Or you might know, but you don’t know what to do about it!

Well, worry not because in this article, not only do we give you possible causes of the smell (for those that don’t know), but also solutions to rid your home on wheels of that foul smell.

You can also check some related articles here that would be helpful for you:

Why does my RV have a sewer smell outside?

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

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

Other sources could give off a similar smell, and we will be jumping right into the details of the stinky situation you’ve found yourself in.

3 Reasons Why The Smell Of A Sewer Is Outside Your RV

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

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

Problems with the Blackwater Tank

When we use the toilet in our RV, most especially when we do a “number 2”, all that waste goes to the black water tank. It holds all the waste that comes from the toilet until you can adequately empty it at a sewer dumping station.

To be clear, the waste coming from the bathroom should be biodegradable, be it solid or liquid. The toilet paper used should be septic or RV safe.

From the function of this tank alone, it’s already a primary suspect. Each of the holding tanks in your RV has a valve with which you use to either refill or empty the tank’s contents, depending on which tank it is. Except yours comes with an in-built RV black water tank flush system which includes an inlet valve that allows you to pump water into it. For your black water tank, you can do the following to check for the smell.

  1. Check the 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 leads to leakages.
  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 out for wet spots because the crack may not be immediately noticeable depending on how big it is.

Greywater Tank

Like the blackwater tank, the Greywater tank is one of the holding tanks in your RV containing whatever comes from the bathroom sinks, kitchen sinks, and water from the shower. Food particles coming from your kitchen sink are biodegradable and can emit very foul odors when degrading.

Sometimes, sewer-like smell. This tank also has a valve for emptying its contents at the dumping station, and the check is similar to that of the black water tank.

  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.

Overcharged Battery

RVs use a type of battery known as lead-acid batteries. This battery constitutes a liquid known as an electrolyte which is sulfuric acid or hydrogen sulfide. This electrolyte helps the battery’s function by taking up a reactant and transporting the medium’s roles through the battery.

(1) Overcharging a lead-acid battery causes this electrolyte to give off hydrogen and oxygen gases. It is a result of the “boiling” that you may have observed. (2) These gases produce a pungent odor very similar to that of a sewer. Some may say it smells like rotten eggs to them. To check for an overcharged battery, do the following:

  1. Check for overheating. Use a glove to do this in case of electrolytes that may have leaked and prevent getting burned.
  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, what’s the use of knowing the problem if you can’t have a solution, right? We know this and therefore have provided viable solutions for each of the issues.

Holding Tanks

This fix applies to both your black and grey water tanks. Loose dump valve: For a loose valve, simply tighten it and ensure that the valve not going all the way in isn’t a result of a fault.

Faulty dump valve: After ensuring the valve of which tank is defective, you can take the following procedure for those that want to “DIY” it, but before that, you will need these essential tools.

Protective gearGloves, eyewear, and a respirator or dust mask for those with sensitive noses or a weak stomach.
LubricantPetroleum Jelly, WD-40.
Cutting tool.Hacksaw. This is for rusted nuts or screws that are difficult to loosen.
Loosening and tightening toolFlathead or Phillips head screwdriver, wrench. Depending on what type of screw or nuts is in place.
Container.Bucket, empty storage container, a can, etc.
  • You should measure the RV sewer pipe diameter to determine its size to make the appropriate purchase which could be either 1.5 inches or 3 inches.
  • Wear a pair of gloves! To avoid waste from the tanks getting on your hands and avoid having a deep desire to burn your hands off.
  • The valve you get should come with the T-handle and extension rod. Be sure it does to be on the safe side. The valves are of different types, so work within your budget.
  • 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 5–11 inches behind the sewer line where you dump your waste.
  • The tank must be adequately drained and flushed to remove any waste. It can be done multiple times if you want the system cleaner.
    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 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.
  • 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 your gloves correctly 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.

Cracked Tank

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

  • Avoid using the toilets, sinks, and showers till 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 the leaking fluids.
  • Dig up any areas that the content of the tank may have spilled into.
  • Lastly, the best advice is to change the tank, but not everyone has a spare $250 – $800 lying around. The next thing to do is fix it. A note of warning, though, the possibility of a fix failing, is always there, hence changing it.

Overcharged Battery Fix

An overcharged battery not only smells bad but is also very hazardous to human health and the environment. It is a result of violent gassing, releasing in excess amounts hydrogen, oxygen, and hydrogen sulfide.

Hydrogen sulfide at non-toxic levels has the familiar odor of sewer or rotten eggs. At acutely toxic levels, hydrogen sulfide can quickly paralyze an individual’s ability to detect its odor and will rapidly render a victim unconscious.

(4) Hydrogen and oxygen mixed in the atmosphere are a ticking time bomb and will explode in contact with fire. So you can see that you have more than just the smell to deal with here. To handle 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 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, or if you don’t have any, one pound per gallon of water of soda ash or baking is a good alternative. Use it around the area of the spill.
  • (3) Ensure the spill has been completely neutralized.
    Use absorbent material to clean the neutralized spill. If there is no specialized material, absorbing clay is a good alternative.
  • 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 the holding tanks?

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

Does overfilling cause leakages?

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 battery?

No, you shouldn’t. An overcharged battery is no longer usable and should be disposed of properly.


The causes mentioned above of a sewer smell outside your RV aren’t the only causes but, as stated, are the most likely. Other things like a leaking propane tank or busted sewer pipes could also cause the smell. So if after you have checked all of this and not located the scent source, then look towards those other options. Are there other causes you can think of? Do let us know.

Whatever interesting or mundane encounters have happened during your travels, It is a great idea to take with you an RV Journal and planner to help you keep track of your journeys. Do check our Etsy store and grab some today!

Here are other articles that would help you as a resource with the things that you need to know about RV:

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    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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