Everything You Need to Know about RV Toilets and Black Tanks

Jul 27, 2020 | Maintenance & Mods

Everything You Need to Know about RV Toilets and Black Tanks

Proper black tank and toilet maintenance is incredibly important for an enjoyable RV experience. It’s easy to do yourself—as long as you understand the basics.

By Stephanie Puglisi

“Taking care of the black tank is my favorite part of RVing,” said no RVer ever. However, the bathroom is truly one of the best RV features and proper maintenance is necessary to keep smells and clogs at bay. The good news is that it isn’t difficult to maintain your RV toilet and black tank. You just need to understand how RV toilets are different from household toilets, use RV-safe materials and chemicals, and follow proper cleaning procedures each and every time you empty the black tank.

Ready to learn everything you need to know about RV toilets and black tanks? Keep reading. 

How is a toilet in an RV different from a toilet in a sticks and bricks house?

An RV toilet is different from a toilet in your home, so maintenance requirements will also be different. A house toilet has a fresh water supply system and is connected to the main drain system that removes waste water from your home into a sewer line or septic system. An RV toilet also has a fresh water supply—provided by either a campground water hookup or the RV fresh water tank—however, the waste empties directly into a black water tank, where it is stored until you empty it. An airtight rubber seal at the bottom of the toilet bowl is all that separates you from the black tank waste. So take care of it, and replace immediately if worn, dry, or cracked. 

What types of RV toilets are available?

The most common type of RV toilet has a connection to your RV water supply, a foot pedal for flushing, and empties into the RV black tank. Premium RV toilets are porcelain, and more affordable models are plastic. Some smaller RVs, like tent trailers and teardrops, may come with cassette toilets. These have a built-in reservoir for fresh water and a small, attached “cassette” for waste. The cassette detaches for dumping the waste into a sewer drain. Another RV toilet option that has become more popular is the composting toilet. These do not need a plumbing system or water supply to operate, making them popular for folks who like to boondock. All waste is deposited into a lower holding tank (or tanks) where liquids evaporate and solids turn into fertilizer.  

A luxurious RV bathroom shot from below.
Premium RV toilets are porcelain, and more affordable models are plastic.

What is an RV black tank?

An RV black tank is a holding container attached to the underbelly of the RV. All of the waste from the RV toilet empties into the black tank (the rest of the waste water from the RV showers and sinks empties into the gray tank). Black tanks vary in size anywhere from 15 gallons to 50 gallons. The size of your black tank will determine how long you can use your RV toilet without emptying the tank into a sewer at a campsite or designated dump station. RVers that plan on dry camping and boondocking should look for a larger black tank or be prepared to minimize use of the RV toilet. 

How do I maintain my RV black water tank?

Properly maintaining your RV black water tank is one of the simplest and most important ways to have an enjoyable RV experience. There is nothing worse than sewer odors in an RV, but if you maintain your black tank, you should never have that experience. Here are a few simple steps to stop the stink before it starts.

  1. Empty your black tank on a regular basis, and especially before you put your RV into storage (whether long or short term). Use the black tank flush RV feature if available on your rig. 
  2. After emptying the black tank, always add fresh water and your choice of black tank chemical. Put a gallon of water along with a chemical pod into the black tank immediately after emptying it. The addition of fresh water is very important as you never want to have a dry black tank.
  3. Never leave your black tank open when connected to a campground sewer hookup. There’s no pretty way to explain this: The liquid waste needs to build up with the solid waste in a black tank in order for it to properly flush out. If you leave your black tank open, you will develop the dreaded RV poop pyramid. Use your imagination. 
  4. Properly winterize your black tank—and the rest of your RV—before temperatures fall below freezing. You will need to make sure all water and waste is removed from the tank before adding antifreeze. 

How do I maintain an RV toilet seal?

The toilet seal creates an airtight seal between the black tank and the inside of your RV, keeping the smelly odors out. Always make sure the seal is well lubricated and holding water in the base of your RV toilet bowl. Only use RV-safe cleaning products to avoid breaking down the toilet seal. Household-style toilet cleaning brushes with stiff bristles can also damage seals. If the seal appears to be dried out, use an RV toilet seal lubricant or plumber’s grease and apply according to product directions. A cracked toilet seal can be replaced easily and affordably. If you’d rather avoid DIY toilet projects, a certified RV technician can do it for you. 

A roll of toilet paper in an RV bathroom
Using RV-specific toilet paper can help you avoid clogs.

Do I need to use RV toilet paper?

If you want to start a war in an RV Facebook group, ask about RV toilet paper. Many people insist on only using RV specific products, while other people insist RV toilet paper is a big rip-off. The difference between regular toilet paper and RV toilet paper is that RV toilet paper is manufactured specifically to dissolve in the black tank, avoiding clogs. Companies such as Scott and Thetford conduct extensive testing to make sure their RV toilet paper dissolves efficiently in holding tanks, and the consumer pays a bit extra for a niche product and peace of mind. 

Is septic-safe toilet paper the same as RV-safe toilet paper?

Some RVers claim that septic-safe toilet paper is developed for the same purposes as RV toilet paper—to easily dissolve in a waste holding tank—and therefore equally safe to use, yet cheaper to purchase. There are differences between a home septic system and an RV black tank system, though, and septic-safe toilet paper is not guaranteed to dissolve in RV black tanks. Therefore, while some septic toilet paper may dissolve just fine in an RV black tank, you can’t be sure that all brands will. Some RVers like to test their septic-safe toilet paper by placing a few sheets of toilet tissue into a jar of water and vigorously shaking it for about 10 to 15 seconds. If the toilet paper begins to dissolve, it is safe for the RV; if not, they won’t use that brand. 

Is Charmin toilet paper RV safe?

Never use regular toilet paper in an RV. This will lead to clogs, blocked sensors, and backed-up black tanks. The difference between regular toilet paper and RV toilet paper is that RV toilet paper is manufactured specifically to dissolve quickly and completely in the black tank, avoiding clogs.

Can you flush toilet paper in an RV?

RV toilets are designed to handle the flushing of RV-safe toilet paper. If you are using RV toilet paper, and flushing with plenty of fresh water, you should never have to battle a clog. When flushing, make sure the toilet paper has completely flushed before releasing the flush lever. This will prevent toilet paper from getting trapped in the toilet seal and keeping it from closing completely. Note that some RV owners refuse to flush toilet paper into their RV black tank, and instead use a trash can with a lid to dispose of their toilet paper. This is completely unnecessary, but some folks would prefer to err on the safe side of black tank maintenance. 

Should you poop in your RV?

RV toilets are designed to handle all human waste, including your poop. If you are properly maintaining your black tank and RV toilet, plus using plenty of fresh water when flushing, you will be able to poop in your RV without experiencing clogs or smells. 

A man wearing gloves attaching a sewer hose to an RV black tank.
Make sure the sewer hose is securely attached to both the RV and the ground sewer connection to avoid leaks or spills.

How do I connect my RV to a sewer?

Every RV with a black tank will have a connection point for a sewer hose. Put on latex gloves and attach one end of your sewer hose to the RV and the other end to the ground sewer connection. Make sure the sewer hose is securely attached to both the RV and the ground sewer connection in order to avoid leaks or spills. Open the black tank valve so the waste can empty into the sewer. It is good practice to empty the gray water tank immediately after to help completely flush out any waste. Make sure to invest in a quality sewer hose long enough to reach sewer connections often located at the rear of campsites. While it is perfectly acceptable to keep the sewer hose attached to the RV and sewer connection at a full hookup campsite, remember to always keep the black tank valve closed until you empty it.

Should I keep my black tank open or closed when hooked up to a sewer connection?

Always keep your black tank valve closed, even when hooked up to a sewer connection. It is critical to have a decent amount of liquid in the black tank when you open the valve to empty it out. If you make the mistake of keeping the valve open, you will develop the dreaded poop pyramid that has plagued many new RVers. The pyramid forms because all the liquid waste drains out, leaving the solids behind. With no liquids and chemicals sloshing around in the tank to dissolve the solids, clogs and smells will develop. Only open the black tank valve when emptying the black tank into a ground sewer connection. Then immediately place fresh water and chemicals into the black tank. 

What is an RV macerator? 

A macerator uses an electric motor to grind up solid waste from the black tank enabling it to flow easily through a smaller hose. The electric motor also allows you to empty the black tank even on an uphill incline since you aren’t relying on gravity as is the case with a traditional RV black tank system. Some RVs come with macerators, or offer them as an optional upgrade. RV macerators can also be installed aftermarket. Many users appreciate the more streamlined hose and dumping process. The most common complaint is not being able to leave the gray tank valve open when parked at a full hookup campground, since you only connect the macerator hose while emptying your tanks. However, many RVs with macerators also have a traditional sewer hookup option that you can use when it is more convenient. 

A gloved hand pulling a lever on a black tank sewer hose.

What is a black tank flush?

One of the most underrated RV features, a black tank flush is a hose port on the RV that essentially allows you to power wash the inside of your black tank. After emptying the black tank, connect a hose to the black tank flush port and spray water into the tank, giving it a good scrub and preventing waste buildup. You should always follow a black tank flush by immediately putting fresh water and chemicals into the black tank. Make sure to have a dedicated hose for flushing the black tank and never use your fresh water drinking hose to do the dirty jobs. 

Why does my RV smell like a sewer? 

If you properly maintain your black tank and RV toilet seal, your RV should never smell like a sewer—but if it does, start by completely emptying your black tank. If the waste is not emptying out of the sewer hose, you most likely have a clog. Use an auger to remove the blockage and then completely empty the tank. Follow with a black tank flush if your RV has that feature. Then add plenty of fresh water and RV black tank chemical. Check the RV toilet seal to make sure it is well-lubricated and holding water in the toilet bowl. It should create an airtight seal that prevents odors from escaping the black tank into the RV. If the toilet seal is cracked or damaged, replace it with a new one.

If your RV is still smelly, you may have a leak where the pipe from the toilet connects to the top of the black tank or an air leak in the black tank vent piping. Lastly, don’t overlook odors that can come from the gray tank. Remember to regularly empty and clean your gray tank as well. 

What deodorizing chemicals should I use in my RV black water tank?

There are a variety of deodorizing chemicals available for RV black tanks. We recommend using Thetford’s Aqua-Kem Toss-Ins with a couple of gallons of fresh water. Look into the scent-free offerings to keep your RV from smelling like a port-a-potty at a summer music festival. Another popular odor-free holding tank treatment is the Happy Campers powder, which claims to be biodegradable and environmentally friendly. A number of RV loyalists use the GEO Method, which entails mixing Calgon water softener with Dawn dish detergent and adding to the black tank after you dump. Some proponents of the GEO Method recommend the use of bleach or borax, but RV experts generally caution against using these caustic chemicals as they can break down RV valves and seals. 

How often should you dump your black water tank?

If in use, you should dump your black water tank whenever your tank sensors read three quarters full. You should also dump your black water tank before storing your RV for any period of time. If you are staying at a campsite with sewer hookups, make sure to dump the tank, complete a black tank flush if possible, and add water and chemical to the tank before departing. If you are staying at a campground without sewer hookups, look for a dump station to empty the black water tank before you leave. If no sewer hookup or dump station is available, search for a place to empty the tank along your route. Pilot/Flying Js, state park campgrounds, and some municipalities offer the service for a fee. 

A red sign pointing to a RV black tank dump station

How do I dump my black water tank if I do not have a sewer hookup at my campsite?

If you are staying at a campsite with sewer hookups, make sure to dump the tank, complete a black tank flush if possible, and add water and chemicals to the tank before departing. If you are staying at a campground without sewer hookups, look for a dump station to empty the black water tank before you leave. Many public campgrounds offer this service for free for campers, but some charge an additional fee. If no sewer hookup or dump station is available, search for a place to empty the tank along your route. Pilot/Flying Js, state park campgrounds, and some municipalities offer the service for a fee. 

Can you use the bathroom in an RV while driving?

Technically, the RV toilet is capable of functioning while the RV is in motion. However, it is never safe for passengers to be unbelted and moving around the RV while in transit. Find a place to park the RV and safely use the facilities. The biggest benefit of having an RV bathroom is never having to use public restrooms along your route. Enjoy the perks of RV living, while also staying safe.  

Can you use the RV bathroom at a rest stop?

You can absolutely use the RV bathroom at a rest stop instead of the public facilities. If you put a bit of water in your fresh water tank before the drive, simply turn on the water pump before using the toilet, and flush as usual. If you do not want to drive with water in the fresh water tank, keep a jug of water in the bathroom to use for flushing the toilet. 


While toilet and black tank maintenance can feel overwhelming to new RV owners, rest assured it will become second nature in no time. Keep it simple, trust the experts, and bring a healthy dose of skepticism to most of the advice you find on social media. Then try to forget all about the black tank and enjoy your RV adventures. 

Black TanksDIYFAQRV Maintenance

Stephanie Puglisi

Stephanie Puglisi is the head of content for Roadtrippers and Togo RV. She is the author of two books—See You at the Campground: A Guide to Discovering Community, Connection, and a Happier Family in the Great Outdoors; and Idiot’s Guide to RV Vacations.

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