Hi there! I’m here to discuss one of the most essential parts of an RV’s plumbing system: the black tank vent. Located at the top of your black tank, this vent stack extends through your roof and is fitted with a removable cap.

Knowing its location is vital – if it’s not in the right place, you could end up with a dry tank from a leaking valve or even a separate vent stack.

In this article, I’ll discuss precisely where to find the RV black tank vent and potential issues that may arise.

So grab a cup of coffee and dive into this essential part of owning an RV!

The vent stack on your black tank is essentially a straight run of 1 1/2″ PVC.

It’s attached to a hole on the top of the black tank and extends through the RV roof. There is, as you know, a removable cap on the top. I can think of several issues you might have:

With the vent stack extending up through your RV’s roof, capped off with a removable cap, you may encounter some issues – but don’t worry, we’ve got solutions!

The first possibility is having a ‘dry tank’ from a leaking valve. This can be fixed by filling the tank and repeatedly flushing it until it gurgles from being full. Then dump the tank and repeat with more flushing – ideally, do this 3 or 4 times after filling with fresh water.

The second issue might be that your vent stack has separated from the black water tank; this can be checked by gently twisting the pipe extending through the roof to see if it moves in your hands.

The third potential problem is that you might have a dirty black tank due to not towing your RV much; this can happen when there isn’t adequate flushing at dumps. To solve this, add some detergent (Dawn works great) and Calgon Water Softener into the tank and let it work for about a week before dumping it out completely again. After doing so, fill and flush several times for the best results.

You may have an airflow issue caused by wind pushing air down the vent stack when you flush – if so, consider getting one of those rotating vents for better ventilation!

Do you have a “dry tank” from a leaking valve?

I’d fill the tank (if you don’t have a black tank flush valve, use the foot pedal on the toilet and repeatedly flush until the tank gurgles from complete. Then dump the tank and repeat with more flushing. Dump a full tank 3 or 4 times after filling it with fresh water.

To fix the issue, you’ll need to fill the tank using the foot pedal on your toilet, flushing it until it gurgles and then dumping it out multiple times. This will help clear any residue left in the RV black water tank and ensure no leaking valve or dry tank.

To get started, here are a few steps to take:

  • Fill Tank: Fill your black tank with fresh water before each flush cycle. Ensure the water level is high enough to reach all tank sides.
  • Treat Water: Before flushing, add a small amount of detergent (e.g., Dawn) into the tank and an RV black tank treatment such as Calgon Water Softener.
  • Flush & Dump: Flush your toilet repeatedly until you hear gurgling inside the black water tank, then dump out all tank contents. Repeat this process several times to remove all residue inside your RV’s black water system.

It may take several cycles of filling, treating and flushing to see results, but following these simple steps can help keep your RV’s black water system clean and functioning properly!

Plus, by regularly maintaining your RV’s blackwater system, you can ensure clogs don’t occur down the line – giving yourself more freedom down the road!

Do you have a vent stack that is separated from the tank?

The 1 1/2″ PVC pulled out of the top of the black tank. Twist (GENTLY) on the pipe extending through the roof, and see if it moves in your hands. If it does, you may have a leaking vent stack problem. I kind of doubt this.

If the pipe extending through your roof moves when gently twisted, you could deal with a vent stack issue that has come loose from the tank. This problem is common and can usually be easily fixed by simply pushing the pipe back into place.

If this doesn’t solve the problem, or if you ca be unable to push it back in, there may be a more serious issue. In this case, it’s best to call in a professional who specializes in RV plumbing and vent stacks so they can assess and repair any damage that may have occurred.

When dealing with a vent stack issue that has come loose from the tank, one of the most important things to do is identify why it happened in the first place. There could be several causes, including age-related wear and tear on the seals, improper installation of the vent stack itself, or even just using low-quality materials when installing it.

Once you have identified what caused it to become loose and disconnected from your black tank, you can begin looking into ways of fixing or preventing further issues. It’s also important to check if any other problems are going on with your RV, such as leaks around fittings or connections, as these can cause your vent stack to loosen over time due to water pressure pushing against them.

Taking appropriate action now will save you time and money, so always watch for potential issues as soon as they arise!

You may (likely do) have a dirty black tank.

This sounds pretty “sophmorish” since all black tanks are dirty…. Since you don’t tow your RV much, you may have a tank that has crud adhered to the side walls from years of use without adequate flushing at dumps.

The only way to remove this is with mechanical action (sloshing water) on the sides of the tank. It’s possible that putting some detergent (Dawn works pretty good) and some Calgon (or other cheaper brand) Water softener in the tank and letting it work for a week or so while you’re gone might help.

Remember, for the detergent to clean, the tank must be full so the water is in contact with all sides and the top of the tank. When you return, dump, fill and flush several times and maybe it will help some.

If my RV’s plumbing starts to smell, it could be due to a buildup of sludge on the tank walls from a lack of flushing. Regularly flushing the tank with clean water and properly disposing of used wastewater is essential for keeping your plumbing system working smoothly. It also prevents the buildup of odors that can seep through vents and other outlets in your RV.

A detergent like Dawn or Calgon water softener can help break down sludge that builds up over time. Be sure to fill the black tank before adding soaps and softeners so there is contact with all sides and the top of the tank. Let this mixture sit for at least one week while you’re away.

When you return, dump as usual but flush several times with fresh water afterward. This should help break down any remaining sludge and keep your plumbing system odor-free.

Regularly flush out tanks with clean water, dispose of wastewater properly, and use detergents or softeners when needed to keep your black tanks clean and functioning optimally!

It may just be that “finally,” the wind is right to push air down the vent stack, and when you flush, the airflow brings a “gentle breeze” up through the toilet…..

There’s not much you can do about that except for one of those “rotating vents” you were considering.

You may notice a gentle breeze coming up through the toilet when you flush – this could be due to the wind pushing air down the stack on your RV’s roof. The vent stack is usually 1 1/2′ PVC and should extend from the black tank right through your RV’s roof. This is where waste gases are released, and if there’s enough pressure, it can create a draft that pulls air back into the toilet.

If this has been happening for some time, then your best solution would be to invest in a rotating vent, allowing you to control the airflow going through the pipe. The rotating vent is designed to open and close depending on how much wind is present or how often you use your toilet.

It can also help prevent rain from entering your RV by directing moisture away from your tank. Additionally, these vents have built-in insect screens, so bugs won’t be able to enter either.

They come in various sizes, so finding one to suit your needs shouldn’t be an issue! With a rotating vent, you can enjoy peace of mind knowing that no foul odors will escape and that any air entering will be clean and fresh – ideal conditions for those seeking freedom in their travels!

Investing in a rotating vent is an easy way to ensure comfort while traveling without worrying about unwanted odors or pests getting inside.

Unless there’s a reason that someone has been tinkering with your vent stack, I don’t imagine it’s damaged;

Probably just an accumulation of crud and that gentle breeze. Try cleaning and flushing. Hopefully, it’ll make your RV a little more pleasant.

Cleaning and flushing your tank can make a big difference in removing that pesky breeze and crud, so why not give it a shot? Doing this properly could ensure your black tank vent is always working optimally.

Here’s how:

  • Make sure you fill the tank with water – if there’s no black tank flush valve, use the foot pedal on the toilet and keep flushing until you hear gurgling from it being full.
  • Add some detergent (Dawn works best), Calgon, or another brand of water softener into the tank and let sit for a week. This will help break down any dirt or grime stuck on the sides of the tank.

After that, dump out all the water, refill again with fresh water, flush several times, and repeat this process 3-4 times.

Take these steps seriously and give them your attention regularly; you can pay off in keeping your RV vent stack clean and free-flowing. Not only does this improve air flow but also helps prolong its life expectancy by preventing wear-and-tear from any debris build up over time.

So don’t be afraid to get your hands dirty! It’ll be worth it for a cleaner RV experience overall!

Frequently Asked Questions

What type of pipe is used for the vent stack?

The vent stack is typically made of 1 1/2″PVC pipe. It’s attached to the top of the black tank and extends through the roof, capped with a removable cap.

How often should I dump and flush the black tank?

I recommend dumping and flushing the black tank every three to four weeks. This will help keep it clean and free of buildup that can cause odors and other problems.

What is the best way to clean a black tank?

I recommend repeatedly filling the tank, adding detergent and water softener, and flushing. Let sit for a week, then dump and flush multiple times. This should help remove the crud from the sides of the tank.

How can I prevent air from coming up through the toilet when flushing?

By cleaning and flushing your black tank regularly, you can prevent air from coming up through the toilet. Add detergent and water softener, fill it, and wash it multiple times. You may also consider installing a rotating vent on the stack.

What can I do if the vent stack is leaking?

If the vent stack is leaking, check for a dry tank; if it’s separated from the tank, then clean and flush with detergent and softener several times. Install a rotating vent to prevent airflow.


I’ve gone over the location of the RV black tank vent and some potential issues that may arise.

It’s important to know where your RV black tank vent is located and what potential problems you might run into.

These issues include dry tanks from leaking valves, separated vent stacks, and dirty black tanks.

The best way to avoid these problems is to be proactive with maintenance. This includes filling the tank until it gurgles at least 3 or 4 times before dumping it, using detergent and water softener in the tank, and flushing multiple times after dumping.

These steps will help keep your RV running smoothly, so you can enjoy worry-free trips for years to come!