RVs & Holding Tanks: 7 Answers (For Beginners)

The freedom to travel with friends and family whenever and wherever you desire when owning a motorhome is incredibly appealing.

However, RV holding tanks are one of the realities of motorhome camping and shouldn’t be ignored.

When you’re a beginner RV camper, likely, you don’t fully comprehend the various aspects of RV holding tanks. If you’re looking into purchasing or already own a motorhome that has a shower, conventional toilet, or kitchen sink, it is equipped with three different types of holding tanks.

In this RV holding tank article, we have rounded up a few of the most important motorhome holding tank questions and have sourced answers for them so that you don’t have to:

1. What Is An RV Septic System?

Interestingly although RVs resemble residential homes, their septic systems are quite different from what you would find in a house.

An RV septic system comprises the three holding tanks your motorhome needs to function correctly.

Usually, you will find all three holding tanks on the underside of your RV. These holding tanks are a freshwater tank, a grey water tank, and a black water tank.

We have briefly described the functions of each holding tank below:

Freshwater Tank:

This tank is for drinkable freshwater, and it comes out of your kitchen and bathroom taps and out of your shower.

This water is also utilized for showering and washing dishes.

Greywater Tanks:

The grey water tank is the one that holds the water from your shower and kitchen sink after it drains.

If you buy an older camper or motorhome, you might notice that it doesn’t come equipped with this holding tank.

Blackwater Tank:

This tank is often the one that scares beginner RVers, but there isn’t anything to be scared of.

In a motorhome, a blackwater tank holds the wastewater from a toilet.

If your RV doesn’t have a grey water tank, all dirty water will drain into the blackwater tanks.

2. How Much Water Can RV Holding Tanks Hold?

How much water the three holding tanks found in a motorhome can hold will depend on the size of the motorhome you have.

Larger motorhomes tend to have holding tanks with larger capacities, but you can purchase a smaller RV with large holding tanks.

On average, a freshwater tank will hold between 20 to 100 gallons, a greywater tank will hold around 50 gallons, and a blackwater tank will hold between 18 to 64 gallons.

3. How Do You Empty An RV Holding Tank At Home?

Contrary to what is commonly believed by RVers, it is not illegal for you to empty your RV holding tanks at home as long as you dump the contents of your greywater and blackwater tanks into an approved residential sewer system.

You can dump the contents of these holding tanks into a stormwater drain. Additionally, if you’re not utilizing a municipal sewer line, you can choose to dup the contents of these holding tanks directly into your septic tank.

You must know how to empty your holding tanks at home as you won’t always have time to do so at a campground. You can’t leave your greywater and blackwater tanks full as they will overspill and create a mess that you likely want to avoid having to clean.

Below we have briefly detailed the three methods you can use to empty your RV holding tank at home.

The Bucket Method

If you want to use the bucket method to empty your RV holding tanks, you can follow the simple steps below.

This method is the most straightforward, but it is also the messiest and the most time-consuming.

If you have smaller holding tanks, this method is one of the best to use, but you should instead opt for the residential line or sewer method if you have larger holding tanks:

  1. You need to equip yourself with protective clothing that covers your face and hands.
  2. Then take your bucket and fill it with the greywater and blackwater but avoid filling it to the top as this will make it harder to carry without spilling.
  3. Once it is filled, carry it to your toilet and empty it into the toilet and then flush it.
  4. Repeat steps two and three until your tanks are empty.

The Septic Tank And Residential Sewer Line Methods

Most RVers have access to a private or public sewerage disposal system.

A private sewerage disposal system works like a septic system, while the public or municipal system utilizes the main sewer line or a residential sanitary line. These sewerage systems use a small pipe known as a cleanout that sticks out from the ground where the sewer line or septic tank is located.

We have detailed below how you should empty your blackwater holding tanks using the septic tank or residential sewer line methods.

If you want to empty your grey water tank, the process is the same:

  1. Look around your property and search for the septic tank or sewer line access port. Once you have found it, you will likely need a large wrench to open it. At this point, you need to put on protective clothing that covers your hands and face.
  2. Next, you should drive your motorhome to the access port and connect a disposal hose to the blackwater tank in your RV.
  3. Once you have connected the disposal hose, you need to connect an output hose to the septic tank or sewer lines access port. Remember to take your time as toxic and harmful fumes could escape when you unscrew the sewer end caps.
  4. After connecting the output hose, you need to ensure it points downward into the access point and is secure so that waste does not escape.
  5. After it points downwards, you can pull the valve to empty your black water tank but ensure it drains completely.
  6. Once you have done this, you can flush the tank and move on to emptying your greywater tank with the same steps.
  7. After emptying your holding tanks, you can rinse the inside of the dumping hose before you disconnect it from the septic tank or sewer line connection and then store it.

The Macerator Method

The macerator method is one of the easiest ways to empty your grey and black water holding tanks at home because it crushes your waste and turns it into a slurry.

If the bucket method is too messy and the sewer line or septic tank method too time-consuming, you might want to use the macerator method, but you will need a macerator pump.

Have a look below to learn how to empty your grey and black water holding tanks at home using the macerator method:

  1. Buy yourself a macerator pump.
  2. Take your macerator pump and connect the macerator input to your motorhome’s tanks waste output by screwing it into place. Then plug in the macerators power cable.
  3. After plugging it in, you need to connect the rinse water inlet to your macerator, usually a garden hose.
  4. Now that you have done this, you must place the hose near a toilet.
  5. Then open your motorhome’s waste outlet valve and switch on your macerator pump.
  6. While the pump is running, continue to our water into your tank until it’s clean.
  7. Repeat these steps to empty your grey water tank at home.

4. How Much Does It Cost To Replace An RV Holding Tank?

The cost of replacing an RV holding tank varies depending on the type of tank you need to replace, its size, and the material it is made of.

To replace a freshwater RV holding tank, you can expect to pay between $100 and $600 for the tank and professional installer fees.

To replace a grey water tank, you should expect to pay between $100 to $1000 for the tank and labor.

For a blackwater tank, you should expect roughly $100 and $300 for the tank plus labor costs of between $65 and $200 an hour.

5. How Do You Unfreeze An RV Holding Tank?

Unfortunately, suppose you don’t have a winterized holding tank system in your motorhome, and you decide to travel during the winter in areas where temperatures drop below zero.

In that case, your holding tanks have a high likelihood of freezing. If your RV holding tanks have frozen, it isn’t the end of the world as you can unfreeze them. However, it would be best if you remembered that while unfreezing your motorhomes holding tanks, you must constantly check for cracks and leaks.

What you need to do is move your motorhome into a protected space where the temperatures are above freezing, and usually, the best place is a garage. After you have done this, you should put on protective gear such as gloves and eye goggles.

Then you will need to use old rags to wipe away any old dirt and insects that could be on the outside of your tanks.

Once you have done this, you will need to obtain a blow dryer, and after plugging it in, you have to use it to slowly thaw the holding tanks to empty them. When you are thawing the tanks, hold the blow dryer approximately six to twelve inches away from the tanks.

In a repetitive motion, while maintaining the blow dryer at this distance, move the dryer slowly from side to side over the exposed tanks. You will need to continue doing this until the contents of the tanks are unfrozen.

6. How Do RV Holding Tank Sensors Work?

If you’re an RV beginner, you likely don’t know much about RV holding tank sensors buy you need to.

Rv holding sensors are crucial as they alert you when your freshwater tank is running low on water, or they tell you when your blackwater and grey water tanks are nearing capacity.

Should you not pay attention to this, or if they break and you don’t realize, you could be left with uncomfortably messy situations inside your RV. So let’s take a closer look into how RV holding tank sensors work so that you have an idea when something could be wrong or so that you know what to monitor.

Generally, RV holding tanks with through wall or probe sensors will be located on or in the sidewall of your holding tank at different levels. These levels are usually 1/4, 1/2, and full.

When the contents of your holding tanks’ drop to each of these sensor marks, your electronic holding tank display in your RV will show you that your levels have dropped. It will do this by conducting electricity when it is submerged in liquid and then lighting up on the corresponding level on the panel in your motorhome.

When these sensors give incorrect readings, it means that you have a problem with either your electronic coach panel or with your actual sensors that are in or on the sidewall of your holding tanks.

However, this is only how the general RV tank sensors work. Other motorhomes’ holding tank sensors work differently, such as electrical resistance sensors mounted on the outside of RV holding tanks and acoustic or ultrasonic tank sensors installed inside the top of a tank.

7. Do RV Holding Tanks Have Vents?

All motorhomes are required by law to have holding tanks with vents.

According to recreational vehicle regulations, every vent pipe must pass through an RV roof and terminate vertically, and it must not be less than 2 inches above the roof.

Typically RV vents consist of 1 to 1 and a half inch ABS piping.


How Much Does A Grey Water RV Holding Tank Cost To Replace?

How You Can Unfreeze Your RV Holding Tanks

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