How Many Gallons of Water Does an RV Usually Hold?

Growing up we always had a camper, but it was on a designated lot with a water tank, but then my family and I finally decided to move it somewhere new and we hit some troubles, one was we didn’t know how many gallons our RV held on its own.

How Many Gallons of Water Does an RV Usually Hold? An average freshwater tank holds from 20-100 gallons of freshwater. A class A RV will hold the most averaging between 75-100 gallons, Class C RV will hold from 35-60 gallons, Class B is around 20-40, Fifth wheel trailers are about 60-80 and smaller trailers are from 40-60 gallons of freshwater.

When you buy an RV you will realize that there are two other numbers besides the freshwater capacity. And the RV class will be a large factor and how much water you will be able to travel with depending on your needs.

What Are the Other Two Tank Numbers?

The other two tanks are your grey and black tanks, so when buying an RV it would say water tank size is 65-25-30 meaning that your freshwater tank is going to be 65 gallons for you to fill up and your grey water can fill up to be 25 gallons and your black should stay under thirty gallons.

Waste gallon sizes depend not only on your freshwater tank size, but also the class of RV. Some RVs are geared at a single person, while others that are family size have larger tanks for everyone’s use.

What is My “Gray Tank?”

Your grey water tank is the water that has been used by the cleaner appliances in your RV. So this would come from your sinks, shower and if you have it, washing machines.

These systems are fed by the freshwater supply and as you use it, goes to the grey tank. Be aware that the grey tank can fill up much faster than your freshwater tank can be depleted.

What is the “Black Tank?”

This is everyone’s favorite part of RVing, the black tank is also known as your RVs septic tank! So the only thing that fills this tank is what comes out of your toilet. Be aware of how full this tank is, and take care of it. Be aware that black tanks can be testy, bring special RV toilet paper to ensure that the least amount of products get stuck in your system.

Also, when first using your toilet in your RV for each trip, fill it with water externally and flush it once. That should get the freshwater system ready to continue to fill it as needed.

How Do I Dispose of the Water in The Black and Gray Tanks?

When your weekend is over and it is time to get down to the nitty-gritty you must first find an approved septic dumping area. (Most RV sites have one available) Hook the waste hose to your black tank or grey tank.

Please make sure to dump your black tank first, then when it is done emptying you can run your grey water. We do this because your grey tank is full of much cleaner water than your black, and can empty out any undesirables from your hose.

But you won’t always be at an RV park, sometimes you will be traveling off the beaten path. This might necessitate you using a portable RV waste tank. This is an external tank, that you can dump your waste into before having to take the waste to an appropriate sewage dump.

Make sure after you dump this portable tank that you clean it completely by running clean water into it.

Black Tank Flushing

After certain periods of time your tank will be full of excess toilet paper and other substance that struggles to empty out with the regular dumping. This will necessitate the occasional black tank flushing. This is most important when you are trying to winterise your RV.

Most RVs come with tank flushing valves, and this is to be done at a normal dumping station. Here you will hook up like normal, but now you will run normal water through your toilet while igniting the black tank flushing valve.

What are the Different RV Classes?

Different Classessleepssizeprice (in USD)
Class A1 to 821 to 45 feet50,000 to 100,000
Class B1 to 417 to 19 feet40,000 to 80,000
Class C1 to 820 to 31 feet50,000 to 80,000
5th Wheels1 to 818 to 40 feet15,000 to 50,000

RV class size is also determined partly by what the manufacturer imagines that you would use this product for. While Class As are more focused on families or luxury. We see that Class Bs are smaller and more for trips where the time you spend in the RV is limited.

How Long Can I Go Between Filling Up and Dumping My Tanks?

This depends on how many passengers you have in your RV for this adventure. If it is just you and one or two more people you should be fine for a week. But just be aware of your tank gauge, it will show you how full your tanks are like a fuel tank would show you.

A safe bet is to empty them out when they hit around 2/3 full. (Be aware that your grey or black might fill up a faster than your freshwater depletes.)

How Do I Conserve Water?

If you have a full RV full of people, but limited resources to empty and fill tanks it is important to learn how to conserve this water.

One of the biggest water wasters is your shower. A tip would be to use the Military style shower.

  1. Just wet your hair.
  2. Turn off the water and run shampoo fully through your hair.
  3. Quickly rinse.
  4. Turn off the water and if you use it, put in conditioner.
  5. Take wet loofa or washcloth and wash your body.
  6. Rinse your hair and body quickly.
  7. Turn off the water and you are done.

This will save so much water, the time shampooing and washing your body is just wasting water. Military style saves so much water and also time. No one wants to wait long periods of time wet, cold and naked.

Other tips:

  • Use paper and plastic plates that you can just dispose of to save water by not having to wash dishes on the road.
  • Use hand sanitizer versus having to wash your hands multiple times throughout the day.
  • Bring plastic water bottles for drinking and other things like brushing your teeth.

Winterizing Your RV Water Tanks

When the RVing season is over, if you do not take proper care of your tanks you can see algea and mold filling your tanks. So when winterizing your tank make sure you use your filtration system to keep everything empty during the periods where you do not use it.

  1. Empty out your water heater first
  2. Locate the low point of your water system to insure that all the water empties.
  3. Use your water pump to make sure that your freshwater tank is completley empty.
  4. Then refill it using a white non-toxic hose with bleach and water. About 1 cup of bleach for 15 gallons of water.
  5. Drain tank again
  6. Fill it with normal water
  7. And empty it to make sure there is not bleach in the water you are later going to use to clean yourself.

Related Questions:

What supplies do I need for my black tank? Before you use your black tank, it needs to have some liquid in it first to keep it running smoothly and to help with the smell. So dump some clean (cleanish) water into it first and then follow that up with a holding chemical.

This helps breakdown the waste in you black tank. There should be directions on the container pertaining to how much you use for your tank size.

How do I tell the black tank is full? There should be a gauge on your RV that identifies how full your tank is. (Similar to a fuel tank) But in the case that the gauge is not working there are a few identifiers.

If the tank is almost full the toilet will almost “burp” or discharge gas from the sewer, this is just releasing the last of the air in the tank to make as much room as possible for waste.

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