Last Updated on April 30, 2024 by Nikole

RV sewage is something no one wants to talk about or even think about. Most of us like to think that once our waste is down the drain, it’s out of sight, out of mind.

Knowing how plumbing works within your RV is essential so you can perform necessary maintenance and upkeep; that way, your family can continue to enjoy your vacation with your RV and without the smells.

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What Is A Black Water Tank in an RV?

A black water tank is what holds all the waste from your toilet. This tank is located underneath the RV and connects to your toilet up top.

The black water tank is designated only for toilet use (not to be confused with grey water for showering, sinks, and sometimes a washer.)

How Does an RV toilet Work?

I know, who wants to understand how sewage works in an RV? Not everyone wants to be a plumber. Good thing is, you don’t need to be a plumber to understand RV plumbing.

It’s essential to know how a black water holding tank and toilet work in your RV; that way, if anything does break, you know what went wrong, or you can avoid smells and clogs.

First Let’s start off with how the toilet works.

Toilet Components

An RV toilet is simpler and quite different from a toilet you would find in a house. The main difference is the way it’s flushed and the water usage.

Toilet Blade

An RV toilet has a blade (located at the lowest point of the bowl) with a gasket that moves when flushing the toilet. This motion allows the waste to enter the toilet directly into the black water tank.

Toilet Pedal

You can use a pedal or handle on the toilet’s side to move the blade (flush it). Unlike a regular home toilet, an RV toilet won’t have as much water, if any, sitting in the bowl.

Leaving water in the bowl, when not in use, is recommended to seal out odors that may escape through the gasket.

To let water into the bowl, lightly press the pedal you use to flush. When you lightly press the pedal, the blade at the bottom of the bowl doesn’t open, allowing water to pool in the bottom of the toilet.

Leaving water in the bowl also helps maintain the gasket around the sliding mechanism. Lubrication helps prevent cracks on the rubber gasket. If you do encounter cracks, you will need to replace the gasket so that smells won’t escape through the bowl.

Where Does The Sewage Go in an RV?

Sewage in an RV gets flushed directly from the RV toilet down a small straight tube (sometimes the tube is angled, this depends on the RV you have) to the black water holding tank.

This all happens with gravity pulling the waste down, that’s why preventing clogs in your lines is necessary for everything to flow correctly.

The water to flush the toilet comes from either the fresh water tank or the city water connection. You can use either connection to get fresh water to flush down the toilet.

Later, when the holding tank is full, the sewage can be emptied out of the valve through a sewage hose hooked up to the RV.

How do you Empty waste in a camper?

Here are the steps you should take to empty and clean your RV sewage system.

Make sure that BOTH the grey and black water tanks are at least 3/4 full before you decide to empty the black water.

• The black water needs to be 3/4 full so the waste has time to break down. The waste needs to break down so you won’t get clogs in your hoses when you go to empty it.
• The grey water needs to be 3/4 full at the time of dumping the black water so you have something to help flush out the sewage.

Step 1

As I stated above, you will need a sewage hose to hook up to the waste fitting located on the outside of the RV. To find the waste fitting, look for two handles, one will be black, and one will be grey. Right below the handles, you will find the fitting.

Step 2

Once you hook up the RV sewage hose to the fitting on the RV, make sure the other end of the hose is fitted to the dump fitting. I will discuss all the places you can empty sewage later in this post.

Step 3

Make sure all of your hoses are securely hooked to both ends (trust me you don’t want any spills).

You should regularly check your sewage hoses because you never know when one will get a hole in them.

I know from experience holes are NOT fun. I didn’t check the hose before we let out the sewage, and there was a hole in it! The entire surrounding area of our camper ended up smelling for a whole day!

Step 4

The next step is to pull the black handle out to release the sewage from the holding tank and into the sewage hose. Wait for it to stop draining; you can hear the flow of water…wait until even the slightest trickle stops, then you can close the sewage trap by pushing the black handle back in.

Step 5

Next is to release the grey water by pulling up the grey lever located next to the black lever. Both tanks are released from the same outlet; however, they are entirely different holding tanks. You can and should release both holding tanks into the same hose.

Like I stated above, make sure you flush out the black water by releasing the grey water last. Doing this helps clean out the hose.

Step 6

There is a black tank flush hook-up around the sewage area on an RV for a garden hose. It’s typically labeled so you won’t get it confused with the freshwater hook-up to the right of it.

This hook-up is for flushing out the entire black tank. The grey water release only washes out the sewage hose; the garden hose will help spray out the entire black tank.

I would recommend flushing out the black tank EVERY time you empty it. I’ve heard others don’t do this but every month or so. However, in my experience, if I don’t do this every time I empty the black tank, the toilet smells.

How to Tell if Your Black Tank is Full?

There are five ways you can tell if your black water holding tank is full; some are more pleasant than others. If one method doesn’t work, then try another approach.

Check the sensor panel

This panel is typically in the kitchen. There are sensors in your black water tank that will let you know how full it is. Click on the black water button, and a light will appear at how full it is.

Alarm

In some RVs, an alarm will sound when your black water sewage is full.

Smell

You can tell when your RV black tank is full when your bathroom starts to smell. When the tank is full, there is less room for odors to climb up from the tank through the hole in your toilet.

The smell also comes from poor cleaning and maintenance.

Use a Stick

Yepp, you read that right; use a stick to check if your RV sewage is full. Open up the disk at the bottom of the toilet bowl. When the stick hits an object, you can tell when your black tank is full.

I wouldn’t necessarily use this as an everyday method, as pushing a stick into your tank and through the pipes could be damaging. This method should only be a means when your sensors aren’t working.

Splash Back

Sometimes your sensors in the tank will break or give you a wrong reading; this can happen quite frequently. If this happens, you can tell if your tank is full when liquid bubbles back up through your toilet when you flush it.

Floor Board Sewage

Your RV sewage can get so backed up that it starts to come through the seal in the floorboard that connects the toilet to the floor. It’s important to check using other methods before it gets to this point.

How long does it take to fill an RV Black tank?

Most RVs and campers have anywhere between 15 to 50-gallon black water tanks. Obviously, the smaller the tank and the more people you have using the toilet, the more you will need to empty the black water.

Below is the AVERAGE amount of time it takes to fill a black tank. There is no accurate way to measure this because everyone uses the bathroom differently. This is assuming that only two people are using the toilet.

How Often Do You Need to Empty an RV sewage Tank?

It’s not recommended you leave waste in your black tank for more than a week. You can go longer (we have gone about two weeks with no problems), but you need to ensure you have the appropriate chemicals and enough water with the waste.

Any more than a week could lead to smell and build-up in your black tank without appropriate chemicals. These smells will also begin to reach your living quarters.

You should aim to flush around .8 gallons of water per time you flush the toilet. This ensures the waste breaks down properly and prevents blockage when you go to empty the holding tank.

Where to Dump RV Sewage

There are several places you can dump your RV black holding tank and that includes the following.

• Campground hookups
• Some gas stations
• Truck stops
• National parks
• Some Sporting goods stores
• RV dealerships
• Some rest areas
• Marinas
• Recycling centers
• City and state dump stations

Most of these areas will cost a fee to dump. Typically prices range from free to $30 per dump.

This RV dump map will show you the areas near you that you can dump your RV waste.

What To Do With RV Sewage While Free Camping?

Sometimes you can get away with not doing anything with your black RV waste tank while you are out free camping. If you find yourself camping well past your time to dump you have a portable black tank option.

Frequently Asked Questions

Here are some questions others have asked us about RV sewage tanks.

How do you dispose of RV sewage at home?

Initially, when we decided to live a full-time camper life, we wanted to use the portable tank I mentioned above. We realized how much it would cost to dump every week, $25 to be exact.

We ended up attaching our sewer to our friend’s home sewage system. As far as I know, this is the only way to dispose of RV sewage at home.

I wouldn’t recommend DIYing a new hook-up to your home sewage system, just hire a professional to do it. It only cost us $500 to get this done, but pricing will differ depending on the area you are in.

How Do I Maintain RV sewage To Keep it From Smelling?

You are sitting in your RV living room watching TV with your family and all of a sudden your nose crinkles from the smell coming out of the bathroom. How do you Prevent that awful smell!?

There are a few things you can do to prevent your RV bathroom and toilet from smelling.

Use appropriate chemicals

Use appropriate chemicals to break down waste and manage smells. Look for chemicals that say enzyme treatment like Campa-fresh, this brand has worked very well for our RV black tank.

At first, We used the Porta-Pack brand that says “holding tank deodorizer” on the pack, and we couldn’t get rid of the nasty smell. I’m assuming that these packs only mask the smells.

Use correct toilet paper

We love our rapid dissolving, Scott brand toilet paper, however, I’ve heard you don’t need RV-specific TP for your toilet. Others have had success with 1-ply TP.

Whatever you do, don’t use 2-ply toilet paper. Using this toilet paper in your sewage system will cause blockage because it won’t dissolve properly.

What is an RV sewage hose?

An RV sewer hose is the hose that connects your RV Sewage valve to the campsite dump station or permanent sewage hookups.

These hoses are necessary for living or camping in an RV; otherwise, you have no way of emptying your RV waste.

I recommend the Camco RhinoFLEX brand, do not go with the other Walmart brand if you decide to purchase your hose in-store.

We purchased the cheap brand and sewage started leaking on the ground due to a hole punched in the lining.

Is RV sewer hose support necessary?

Support for your RV sewer hose is necessary for dumping. The support goes from high to low so gravity guides the waste from your tank to the dump site.

A Support also…. supports your hose. There is less pull from waste going into the hose, meaning your hoses could last longer.

We lived without support for a week and we had to hand guide the sewage through the hose to the sewer.

Can You Travel With A Black Tank Full?

You can travel with your black tank full. I wouldn’t recommend you travel with it full to the brim, however. This could cause a backsplash when stopping or turning.

Traveling with your RV sewage system full may be your only option, especially when you are boondocking and there is nowhere to dump the waste.

How do you hook up a House sewer to a camper?

I really like what Jeffsetter Travel has to say about emptying your RV tank into a house sewer. Remember to look up your local laws and regulations before you decide to do this.

Should You Keep Water in Your Black Water Tank?

Water helps to break down the waste faster. After emptying your tank, close the valve connecting to the sewage hose. Immediately flush some fresh water and an enzyme down the tank. TMI, but you don’t want any “flapjacks” getting pasted onto the bottom of your black tank.

You should leave the water and an Enzyme product in your black water tank when storing your RV or when not in use.

If temperatures reach below freezing you should winterize your RV and leave water and treatment out of the tank.

How do I clean my black water tank sensors?

Quite often, I hear people complaining that their black tank sensors read full when they just emptied it. Toilet paper or residue might be stuck to the sensors.

Cascade or other automatic dishwasher detergents work well to clean tanks. Here are the steps you can do to clean off your RV sensors.

1. Fill your RV black tank halfway with water.
2. Squirt some of the detergents into the tank with the water. Just squirt it through the toilet.
3. Drive around to agitate it, this will help loosen up whatever is lying on the sensors.
4. You can repeat these steps but with a few bags of ice instead of soap.

If you are in a permanent location and can’t drive around like us, you can use a spray wand specifically for cleaning out your RV’s black water tank.

Can I leave my black tank valve open?

The only thing stopping the waste from your RV black tank from pouring into your sewage hose is the valve. To open the valve you lift up a black handle and the sewage will flow out of the tank.

Other than when you empty the sewage I would not recommend leaving the valve open. You need to have some water in the black holding tank in order for waste to properly dissolve.

Can I Dump RV Waste On the Ground

Absolutely do not dump your RV waste on the ground. This is extremely unsanitary and bad for the environment.

Always empty your black water tank into a designated area.