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What Size are RV Holding Tanks?

What Size are RV Holding Tanks?

RVing can be a great adventure, but also where you can pay the price of inexperience and ruin your own vacation if you do not know a few things about your recreational vehicle before you buy it. One such thing is the different sizes/capacities of RV holding tanks.

So, what size are RV holding tanks?

RV holding tanks (freshwater, gray and black) are between 4 and 150 gallons depending on the type of tank and the size of the recreational vehicle. 

If you are feeling confused by this answer don’t worry. We will get into all details of RV holding tank sizes.

RV Holding Tank Size

They range from just 4 gallons and can be bigger than 150 gallons. It all depends on their type and how much room is available for them in an RV. There are three types of holding tanks:

  • freshwater tanks
  • gray water tanks
  • black water tanks

So, let’s get into a detailed discussion of these types of holding tanks.

Types of Holding Tanks

On any recreational vehicle, there are three types of holding tanks. This is because the things that are stored in them are not supposed to mix with each other.

40 gallon black water rv holding tank –

It is not sanitary to do so and can lead to many health problems if the contents of these tanks get mixed together. And there are also some practical reasons to keep them separated.

Freshwater tank

This is the tank that holds all of your potable water supply. If you are dry camping away from civilization and the convenient water supply of the campgrounds, this will very likely be your sole drinking water supply. But this water is not just for drinking, and you will be using it for other things for which you need clean water.

30 gallon freshwater RV holding tank (A.A)

Gray water tank

Gray water is the wastewater you will be producing when using the freshwater for other things besides drinking and cooking. Things like washing dishes, showering, and if your RV has a washing machine, its wastewater will also be disposed of into the gray water tank. This wastewater is stored in a separate tank from other wastewater for convenience. It is much more practical this way.

Black water tank

This tank holds the wastewater from your RV toilet, no matter how disgusting it may sound, but if you do not have a proper way to dispose of it, it’s more sanitary to keep it safely stored in the black water tank. If you are in nature you might think it is OK to just dump it, but it isn’t. Waste will attract pests, but also contaminate your immediate surroundings.

How big are the standard RV holding tanks?

Now that you know what the three types of holding tanks are for, we can move on to the matter of how big the standard ones that you can find on recreational vehicles are. Their size almost perfectly correlates to the type and class of an RV, which is also closely related to their size and occupancy capacity. Let’s see what you can expect from holding tanks.

Also read: What is the Difference Between Class A, B and C Motorhomes?

Class A Motorhomes

Class A motorhomes are the largest class, and they can have the highest number of sleeping spaces allowing for the highest occupancy. If you are guessing that they will have the largest holding tanks of all motorhomes, you would be right.

Freshwater tanks usually range between 70 and 95 gallons, gray water tanks are usually between 45 and 70 gallons, and black water is between 30 and 50 gallons.

Class B Motorhomes

Because the Class B motorhomes are the smallest type, their holding tanks will also tend to be much smaller than the other motorhome classes.

From a freshwater tank you should expect to hold 15 to 35 gallons, sometimes even 40. The gray water tank can range from just 8 gallons to 30 gallons. Black water tanks can be “tiny” 4 gallons or up to 25.

Class C Motorhomes

The letter C does come after letters A and B, but the motorhomes of this class fall between A and B in their size. The same goes for their holding tanks. The most common sizes for freshwater tanks are between 30 and 55 gallons, for grey water tanks between 35 and 60, and for black water 25 to 45 gallons.

Teardrop and Pop-up Campers

Teardrop and pop-up campers are the smallest types of RV trailers, and they are always designed with maximizing the space in mind. Because of this, they sometimes have just the fresh water tank between 4 and 10 gallons. But usually, they don’t have holding tanks. But these trailers are not designed for long trips by large groups of people, so their utilitarian design is usually good enough to do the intended job.

Travel Trailers

The travel trailers are much larger than the teardrop and pop-up types, but they range from slightly larger to quite a lot larger ones.

So their holding tanks can have a very wide range of sizes too. But, there are some more common capacities, just as their size is usually this much. Fresh water tanks commonly hold 35-65, grey water 40-60, and black water 30-40 gallons.

5th Wheel Trailers

The 5th wheel trailer makers are putting a real effort to make models that are larger than Class A motorhomes, thus their holding tanks very commonly are the same size or even the same ones installed in Class As. Freshwater tanks tend to be in the 55 to 95 range, grey water in the 50 to 85, and black water tanks 40 to 80 gallons range.

RV Holding Tank Size Requirements

How big tanks you need depends on how many people will or can use an RV and for how long you plan to dry camp. Some rough estimate is that you need a gallon of drinking water per person every day, another gallon for cooking and basic hygiene per day, and 4-5 gallons for every planned shower.

As you can see from this split, you can expect every 6-7 gallons of fresh water to create some 5-6 gallons of grey water, and at least 1 gallon of black water, but for obvious reasons more likely 2. Based on this you can calculate your actual needs.


Closing Thoughts

What size are RV holding tanks is something you should know as their capacity is setting the hard limits on your ability to RV completely independently of campground connections and supplies.

There are three types of holding tanks, and their sizes depend on how big the RV is and how many people it is intended to house. Their capacity can range from 4 gallons to more than 150 gallons.


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(Featured image: A.A/

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